I am also in the process of painting my interior pieces black. There's many ways of doing it. I have chosen to do it the cheapest way possible which is to take off the pieces, give them a good cleaning with soap and warm water and wet sand them with fine sandpaper. After it dries up really good I spray the pieces with a can of adhesion promotor which I buy at Autozone. After two coats of the adhesion promotor I put three light coats of black Kyrlon fusion and then two coats of clear. I did my pillar gauge pod that way a few years ago and the paint is still perfect. The Krylon fusion is really good because it eats into the plastic which makes it stay permanently and not flake. You won't get the professional smooth look but it will look good for a cheap price.