One way to do this and have it turn out perfect is to use Varikote, a German product available in the US from
Parasol.
Ideally, you'll want to send in a sample for color matching. You can apply the dye with a spray gun attached to your air compressor, or buy it in aerosol cans. The latter will be more expensive as I believe there is a minimum for custom colors.
Lots of light coats. The nice thing about dye is it penetrates the pores of the plastic, and looks absolutely factory when done.
