Painting my plastic was not a big problem, I simply prepped the hard surfaces by sanding, primed w/ KILZ, used plain ol Krylon Hard hat, haven't had a single scratch or peel. Baked all the parts in my own oven. as far as the the softer materials, latexes combined with good latex primers will do fine. Some of the softer acrylics will work too.
Talk to your local PPG rep, or contact them here with specific questions . . .
http://www.ppg.com/con_main/con_carauto.htm