is the kit plastic or fibreglass?
if it's plastic it's very somple, just give it a gray scotch, clean it with plastic cleaner then spray sp,e plastic primer then treat it like any outher color. If it's fibreglass i would bake (at about 40 anything else is to hot for fibreglass) it first because they seem to get massive pin holes in it, then prime it and bake it again, rub it bake and then treat it like any other panel. if it's fibreglass it may come already primed and if it does you can rub that and paint over it but at work we have found it's alot better to reprime it otherwise it tends to pin hole or leave bubbles which will just chip off