mine had a clear coat on them and the black paint so you will have to strip that off then get some polishing compound.i used two steps the first compound was for taking out scratches and stuff than the other compound was for the finish.you will probably need a bench grinder with buffing wheels on it.you cant use one wheel for both compounds.
the first step compound will need a tight stitch buffing wheel and the finish compound will need a loose wheel.
the buffing compounds are not like a polish for your car they are a hard stick kinda like a clay bar