I painted my calipers and I wasn't too happy with the results, but it'll keep me satified b4 I go powdercoat them. Anywayz, here are the steps I took to paint mine.
Take off the caliper, apply brake cleaner, clean with simple green and wire brush, wash off, let dry, paint them applying about 4-5 coats, let dry, apply 1-2 coats of clearcoat, let dry, done.