Here are the supplies you will need:

~7oz. Can of Nite Shades Tail Light Paint
~Dish Soap
~Water
~Masking Tape
~Newspaper
~Steady Hands
~Cotton Towel
~Paper Towel

1. Wash rear of car with normal carwash/water
2. Mix water and dish soap together and wash the tail lights really well (this will remove all the contaminates and wax and whatever else is on there)
3. Rinse Of Rear of Car and taillights
4. Dry Very Well with cotton towel (make sure no lint is on the tails)
5. Mask Area with masking tape and newspaper
6. Shake can of Nite Shades for about a minute
7. Keep the can about a foot away from the outside of the taillights while painting, start on the newspaper and make quick strokes across the taillights. (if you start painting while the can is aimed at the tails it will come out too fast and start to run)
8. Make several VERY light coats.
9. Wait 10-15 min and spray another light coat
10. Repeat until you are happy (usually 3-4 coats, but remember it dries darker, takes about 8 hours to fully dry)
11. Take off masking Tape and Newspaper
12. Let dry for a few hours

I did this all without taking out the taillights, it would probably be easier to paint with them out but it is not necessary for good results. I used 3 coats on my taillights. I bought the paint from Modern Performance and it was 13$ including shipping. I could not find the paint locally, but they may carry it at some performance shops. The lights are still quite bright at night, slightly darker during the day. If you do put too much paint on the lights in a certain spot and its starts to run just VERY LIGHTLY dab the paper towel over the spot to soak up some of the extra. Then apply another very light coat to that area to cover it up. It will cover up after several layers so take your time. If you really mess up, this stuff just comes off with Nail Polish remover. It doesn't even cloud the tails. Some people also clear coat the tint (for protection and shine) but I haven't had any problems with just the tint on there. This will also make the tint permanent which I don't want to do quite yet. Here are some pictures of my lights:
 

-Josh