Here's the step-by-step instructions:
Part 1 - Trunk
The trunk is the easiest place to work in, and most likely the part of the car that will benefit the most from the ultra-bright bulbs, so we'll start here.
1. If you have the premium lighting package, then you will have three bulbs in the trunk/boot; one facing down from inside the hatch, and two in the trim below the loading shelf; one on each side, facing inwards. Proceed to step 3. If you do not have the premium package, you'll only have the bulb in the hatch. The good news is that Tesla still ran the wires for the other two locations (yay), but you have to work a little to find them (boo), and locations vary, depending on the age of your Model S. If you are not comfortable removing trim pieces, stop now, and seek professional help. This is an easy process, but some owners understandably do not like pulling bits of their car off.
2. If your car is 2014 or later, you should be able to pull the soft black trim away to reveal the light connectors. If you have an earlier model, then you might have to pop the loading shelf off, for this you'll need some heavier-duty trim removal tools. You should find the drivers' side connector secured with black tape under the charge port (not silver tape). This is a high-voltage area, so although everything is shielded, do NOT work in this area when charging the car. The passenger side light is normally tucked into the corner, towards the opening of the trunk. Both wires can be identified by the presence of a 2-pin connector - please refer to the photos.
2a. You will also have to remove the punch-outs for each of the lights; the locations are shown in the photo above. You can 'feel' the punchouts by applying pressure in the general area shown in the photo; then remove the punchouts by either pushing them out, or carefully using a pair of scissors to free them.
3. Starting with the hatch light, find your spudger and wedge it into the small recess on one of the shorter sides on the bulb, as shown in the photo, then simply pry the bulb out. The spudger is plastic and doesn't have any sharp edges, but if you're concerned you might scratch the surrounding plastic, just add a small piece of masking tape over the 'pry area'. On later Model S's, this location has become more challenging as the trim fit is much tighter. IF the spudger doesn't work for you, consider using a small flat-blade screw driver to pop the bulb out, but ensure you've protected the surrounding plastic with masking tape. Using a screwdriver might crack the outgoing factory bulb, so proceed with caution. For the other two bulbs, since they're in the soft trim, they'll come out very easily using the spudger, or if you're tough, just use your fingers to pop them out.
4. Disconnecting the old bulb is very easy when you know how. The picture shows a small plastic lever that's part of the 2-pin plug. Simply push that down with the spudger or a finger nail, and the connector should release. If it doesn't, just pull on the bulb a little as you're pushing down on the connector. Once you've done this once, the others will be a breeze.
5. To install your new ultra-bright bulbs, simply push them onto the connectors until you hear the click of the plastic pin popping back into place. Depending on how long you've taken so far, the lights might have timed out and gone off, so don't be alarmed if you're not immediately blinded by the new lights, just close and re-open door to turn them back on.
6. Finally, push the lights home into their socket by using two thumbs to push them in with equal pressure on each side. Do not fully push one side in, then the other, as this might cause the plastic to crack.
Part 2 - Frunk
This one is easy. There's only one bulb, located below the locking latch on the leading-edge of the frunk.
1. As before, find your spudger and dig it into the small nook on the shorter edge of the bulb, then just pry it out.
2. Remove from the connector as described in Step 4 above. Then don your sunglasses and install your ultra-bright bulb as described in Step 5 above, and push the bulb back into place as described in Step 6.
Part 3 - Puddle Lights
If you have the premium lighting package, then each door has a white light on the bottom of the door trim shining onto the ground. If you do not have the premium lighting package, then we do not recommend trying to find the wires and removing the punch-out from the doors; seek professional help.
1. You're probably going to have to lay on the floor to do these, so park your Model S in the living room, or find a nice bit of carpet to lay on.
2. The door trim is quite soft, so the bulbs pop out as described in Step 4, and then follow Steps 5 - 6 to complete the installation. You will need to use some force to get the spudger under the bulb to extract it.
3. Keep the carpet out to kneel on if you're planning on doing the foot-well lights....
Part 4 - Foot well lights
There's four of these. The front ones are located in the trim directly above where your feet hang out, which on the drivers-side means that the pedals get in the way a bit.
The rear ones, are fitted to a small plastic bracket that sits on a bar below the front seats. In early Model S's the rear lights were part of the premium lighting package, so you might not have them, but the wiring is there. You might need the bracket that snaps onto the bar as shown in the photo. You can purchase the brackets here. Newer Model S's (April 2017+) have a different assembly under the seat with an integrated bracket, so please check before purchasing. Please note the integrated bracket forces the light to shine directly downwards; there's no way yo adjust it, but some customers have used zip ties to secure the bulb to the bar at a more useful angle. Our bulbs still fit the bar, so all the more reason to have them :-)
1. Let's start at the front. Now you've done a few of these bulbs you're a pro. That's good, because the drivers' one is a pain to pop out because the pedals get in the way. The technique is still the same though, you just need to really dig the spudger into the small nook on one short side of the bulb, and pry it out. It might take a few tries, but it'll come. The passenger side is the same, but easier without the pedals to get in the way. follow Steps 5 - 6 above to complete the installation.
2. To the back of the car we go. Raise the seat you want to work on to its highest position, and then tilt the seatback forward as far as it will go. If you have the newer "next gen' seats, ensure the headrest does not put pressure on the sunvisor in the fully tilted position. If you do not have the premium lighting package, then the cables for the lights are likely tucked up under a flap under the seat - they're there, just feel around until you find a free 2-pin connector.
3. You can then see the lights, fitted into a bracket that snaps on and off a support bar. Note the position; they're installed with the light at the top, shining downwards.
4. To make the replacement easier, disconnect the power cable (it's the same plug as all the others), and pull the bracket, complete with the bulb, away from the bar. The clips holding it on the bar are mean and angry, so mind your fingers (the author speaks from experience).
5. Now pop the bulb out of the assembly. You'll need to use the spudger to do this, and also try to squeeze the clips that are part of the bulb inwards to help release it. The bracket is very rigid plastic, so the bulb needs a little more encouragement to pop out.
6. Once you have the bulb released, replace as described above, refit the bulb and then the bracket to the support bar. To save your fingers, the best way of snapping the bracket back onto the bar is to get a thumb behind each of the 'clips', and firmly push with even but strong pressure, to force it over the bar. It really does take a bit of strength to do it, but don't worry, you're not hurting the bracket. Repeat the same for the other seat.
Bonus Part 5 - Glove box
If you want a dazzling glove box, you can also replace the bulb in there. The process is the same as described above for all the other bulbs, but the bulb is quite difficult to remove; if the spudger doesn't pry it out, you might need to revert to a small screwdriver, but in doing so you might crack the old bulb, so take care.
Finally, if you need more help, then please take some time to read the discussion on the Tesla Motors Club; this link drops you into the middle of the thread, and you'll find a huge amount of helpful information and photos.
Q. I'm having problems making the plug click into place
A. As long as the plug is secure in the bulb, then you'll be completely fine. Over the past five years Tesla has used three variants of plug, which are broadly the same, but mean that the socket on the bulb needs to accommodate all the options. Generally it will still click home if you apply some force, maybe using a spudger (rather than your finger), but again, as long as it's snug in the socket, it won't go anywhere. We've sold well over 50k of these bulbs to S, X and 3 owners, and have very few issues with them, so we're sure you'll enjoy them for many years to come :-)