I don't know if this is all that relevant but there's a place that does professional work on tail lamp tinting / smoking. I'm pretty sure you could email them and ask about clear corners and etc. being tinted for a certain price if negotiable. If you truly want to do it yourself then go with VHT NightShades. It's specifically made for plastic. Also look into using "Clear Coat" from Testors so that you have that glossy look rather then it being dull and fading over time. Your best method would be to test VHT NightShades on a test material if you have the money for it, by sanding down the plastic then going over it with a moist rag to remove any particals left behind. Then do a light coat with the spray, alow it to dry, and go over with another light coat and continue the process until you get the right shade you're looking for. After it dries for 24 hrs, Apply the clear coat "gloss" paint and do about 2 coats. The clear coat should protect the Tint paint from fading as quickly.

The website that does profession work on the tails lights is @ http://www.smokinlights.net