if you want to try buffing it i suggest wet sanding it with 2000 grit and then using a buffer on it, it may or may not work depending on the condition of the plastic. if you want to paint it i suggest scuffing it with a red scuff pad and then wash it with hot water and dawn dish soap, this will help remove the mold release agent thats in the plastic and is the reason its so hard to get paint to stick. once its washed use an adhesion promoter( heres what i use with excellent results
http://www.amazon.com/Kleanstrip-ETP...esion+promoter) and follow it up with your paint of choice.