can't help you with the paint code, but you may want to check out this how-to for an idea of what is possible. personally, i'd probably just repair the rash/gouges and spray the entire wheel to get perfect even coverage then top it with 3 coats of clear. i believe duplicolor makes a couple different shades of silver/gray in their wheel paint.
Unless your going to get paint mixed, its going to be pretty hard to find a spray paint or touch up paint to match the rims. Even color coded touch up paints don't match, and they'll stick out. Like stated above, I'd spray the entire rim with paint. Very easy to do, especially if your just using spray paint
If you have painted BBS wheels a match would be Wurth's silver lacquer paint, might be worth a try. :noidea: Some people also use the color vogue silver from Acura to repair curbing on silver painted wheels.