i've done this on both my CRX and RSX and i've found the process MUCH easier than using stained glass paint to achieve this effect (which i have also tried with less than desirable results).
so without further ado, here's my first how-to!
-glass or all-purpose cleaner
-transparent red vinyl (a one foot sheet was plenty for me)**
-mixture of liquid dish soap and water in a spray bottle
**the only place i was able to find transparent red vinyl for sale online was here, they sell by the foot: http://www.importequipment.com/stick...ransparent.htm
there may be other places but this was the only one i could find in several days of searching. you may also be able to find some locally.
thoroughly clean the area where you are going to apply the vinyl. i like to use Spray Nine, but any regular glass or all-purpose cleaner should do.
cut a piece of vinyl a little bit bigger than the amber area you want to cover.
spray the area with the dish soap and water mixture
place the vinyl on the wet surface
using your fingers and the hair dryer press out the bubbles and water. the heat from the hair dryer makes the vinyl pliable so you can stretch it around awkward curved areas without wrinkles. if you get a wrinkle, peel back the vinyl, heat it with the hair dryer and reapply it to the surface. this is why you put the soapy water on first, so it doesn't adhere right away. you may need to add more of the soapy water if you are repositioning the vinyl a lot.
once smoothly applied, use the razor blade to trim the excess vinyl. with the CRX lights this is made easy since there is a groove around the amber area. go slowly and be careful not to scratch the plastic. if you have some wrinkles still, it is usually easier to smooth them out after the excess is trimmed. you will probably have to trim again but you will get a nicer finished product this way. when all trimming is finished, use the hair dryer to help "seal" the edges.
then put them in your car!
the full effect:
edited with some more pics:
some pics of my RSX on which i used the same process - click the pics for a bigger version:
the whole process took me about half an hour to do both tail lights. if you later decide you don't want all-red tails, just peel off the vinyl. you may have some adhesive residue depending on how long you had the vinyl on the lenses, but they should look stock again without too much effort. i've had the vinyl on my RSX tails for the last year and a half and it has not noticeably faded, peeled or otherwise degraded in appearance.