There's a really detailed explanation (with lots of photos) at http://celicagarage.com/forums/viewtopic.php?t=1185
Here's a writeup of my headlights paint job. I'll include tips and things I learned along the way. I did them in gunmetal, using Duplicolor wheel & rim paint. The color was "graphite" I chose wheel & rim since it was the only one at that store that came in graphite. Looking at the can, it says for wheels and PLASTIC hubcaps, so I knew I was in business. First off, wear gloves, they get hot, being in the oven & all. And wear some old junky clothes because you'll probably get some epoxy on you.
Here's a pic of the can of paint I used. It might be different in the USA, but I picked it up at Canadian Tire for like 7 bucks.
So here I am in the garage, first order of business is taking the bumper off, and then removing the lights.
Tip#1: undo the silver screw on the side by the fender last, it supports the light while you take out the top & bottom screw.
Everyone knows about the 3 brass screws, but there's also 2 little rubber nozzles with sponge filters I was NOT expecting to see. Take these off too since they probably wouldn't fare too well in the oven. In the top pic, one is shown along with the DRL which I also removed. Second pics show's them removed. (obviously)
And the top one, along with the lowbeam rubber seal which should be removed along with the bulb, as in the next pic (yeah the bulb's still there but I did take it out)...
Take out the 3 screws on the lowbeam seal and it comes right out. I'm not sure what the hell those other 2 things are but they didn't seem to be going anywhere so I left them. Survived the oven fine so no big whoop.
Next comes the oven.
Tip#2: place the towel on the rack and "pre fit" the light in the oven with it off. Then you have an idea how far into the oven it has to go.
Turn on the oven to 300F. When it hits that temp, open it up, stick in the towel, and place the light on the towel so it doesn't melt on the rack. Have the rack on the lowest one. I used "bake" instead of "broil". Turn it off, close the door and start the timer. I left it the full 15 minutes before I took it out.
Tip#3: don't be afraid to get some help. I had my kid help me take them apart, his job was to unclip the clips on the side of the light with a butter knife while I pulled. ALSO, VERY IMPORTANT... Start at the top, when you get the top opened a bit, stick the knife in between and jimmy it open. The rest should go as smooth as can be. The sides of my light didn't get wrinkled at all like you sometimes see. I just kept pulling and pulling. Only had to do it once, didn't have to reheat the oven. But leave it in the full 15 minutes. Use an old butter knife as it gets some gunk on it. Here's one of the lights apart...
Tip#4: to take the insides out, remove the 2 screws, the jimmy it apart. Start at the top, be careful since you don't want to break the damn thing. When you put them back together you'll notice it just sort of drops in from the top and snaps into place, so do it reverse to take it out. The side opposite the screws has a little tab. Note it's path, it needs to be pulled up. It will take a little fiddling but it comes out. Then bend up the tabs carefully on the reflector and take it out. The single tab will lift up first, and then you can pull it out. Don't get carried away bending it up and down since it will get weaker each time you do and eventually break.
Next up...decide if you are going to paint the top or the underside. I wanted the ribbed look, so I decided to paint the underside. This being said, it's wise to totally mask everyting on the top, since as you spray it goes pretty much everywhere. Take your time, do a good job, we're only going to do this once... right? Don't worry, if you fcuk it up, you can always paint the top.
Flip it upside down, paint it someplace dry and not dusty, if you're doing it in a garage, pull any vehicles out since paint might get on it. Stands to reason right? But you never know. When it's upside down, you can see if you missed any spots.
Tip#5: On the first one, I tried to follow every curve perfectly with the masking tape. On the second one I let it overlap, with the overlap hanging in the air. I made sure that it was on tight by running my fingers over top and pressing it down really tight. By spraying light coats, it sholdn't wick paint under the crack. It didn't for me, but again, I pressed it down really well.
Next, paint the mofo. Use light strokes, again, take your time and do a good job. You don't want it running all over. I did 2 coats. Took a while on each coat to get it all, and then waited oh, about 1/2 an hour between coats. Then let it dry a couple of hours or so.
Wait until it's dry and then peel the tape off. Take care as some paint on the tape might be wet. You don't want to get it on your hands or on the light. Once it's off admire it. Damn that's a thing of beauty.
Tip#6. If there's little bits of glue from the masking tape, or epoxy on the outside, use duct tape to remove it. Yup, duct tape, is there anything it can't do?? Take a little piece and stick it over the leftover adhesive. Then peel it back. You'll see it pick up a bit. It will take some time but it will totally remove it. It's better then wiping it off with windex, or rubbing alcohol, or what-have-you, since it takes it off clean instead of spreading it around.
Put it back together now. Before you do, take a bit of windex and clean it up. ALso make sure the painted part is totally clean and everything is clean. I got the second light together and was giving it a once over before I stuck it back in the oven and wouldn't you know it. There was a damn HAIR on the inside of the light. REALLY look at it at this point, since you REALLY don't want to pull it apart again.
Insert the reflector and bend the tabs back down. Do the double tab side first then set it down on the single tab. Next, slide the painted part into the clear light cover. If the light were on your car, slide the painted part down, and you'll see how that tab clicks right into place. Then press the other sides down and put the screws in.
Next, place the 2 halves together, be careful and line them up properly. Even though it is cold, the epoxy still sticks together pretty good. I heated the oven back up to 300, and this time put them in for 8 minutes since I didn't want to melt the paint or anything. (I don't know if that would happen but I didn't want to take the chance) When it comes out press it together and the pieces should slide in nicely. Put the 3 brass screws in at this point and it will really suck the whole thing together. Here's some pics of them done...
And both lights together, completed.
Replace all the little rubber filters, the DRL's and the rubber seals for the lights.
Tip#7: put your lowbeams in before you install the lights back on the car. WAY easier.
Slap them back on the car...
Put the bumper back on and voilla. Easy mod, I'd do it again in a heartbeat. Set aside a day to do it, since the painting takes the time. But don't be afraid. I was hesitant at first but it was a piece of cake. Having a helping hand when you take it apart might be all the difference in the world.
A couple more pics of the final product. Oooooooooooh... Aaaaahhhhhhh. Yeah it looks great, and will go great with my Carbon Fiber hoodscoop (which is in getting 6 coats of clearcoat) and my gunmetal rims which I should be buying any day now. Really, like ANY day now, I mean it, like totally.
Rock and roll. Hope this helps out with some of the details and tips & tricks.