Yeah the Duplicolor interior paint works great! I used that on a faded dash in my S10 i used to have, it was badly sun faded on top, whitish in places, etc.
Pulled it and wiped it down with some prep-solv, thats a brand name i think as it comes in a can with that name on it, its basically acetone like they wipe stuff down with before painting at a body shop. You just have to be CAREFUL with the plastic though because some plastic will melt with acetone.
They make another surface prep specifically for plastic, usually you can find it in a spray can right by the Duplicolor Vinyl and Fabric paint. It works great, bonds and doesn't peel. I was skeptical so i painted a small end panel of the dash first and after it dried you couldn't scrape the stuff off, it like melts into the surface and really bonds to it, its not like a paint, its more like a spray dye if that makes sense.
Stuff stinks like hell though, well ventilated area and use a mask. The worst part of the job is just removing stuff to spray it. I've done dashes, steering wheels, door panels, etc.
