The stuff I used was Duplicolor gloss black vinyl dye. I got it at Canadian Tire, but I guess you don't have that in the states. Autozone or whatever should carry it. I used 3 cans on that car. It's a spray bomb, you just spray it on.
Like was said, make sure the parts are CLEAN to allow the dye to soak in. If you can, clean it with something that will dry the surface out slightly, like an alcohol. This will make it more willing to soak up the dye. I just cleaned it with soap and water though. No Armor-all! It won't stick.