The G2 system is pretty popular. I used it on my car and it's a snap to do...then again my car only had about 1500 miles on it when I did this. You can pick it up at tirerack.com in your choice of colors. Go to
http://www.tirerack.com/brakes/g2/caliper_paint.jsp
As for prep, just hit the calipers real good with the brake clean spray in the kit, and brush with a stiff brush to get the heavy stuff off. You can always pick up more brake cleaner at any autoparts store for a few bucks, but it goes a long way. The paint itself is a two part mix and you brush it on. Works really well.