First of all the obvious, use safety precautions. Jack and support your vehicle accordingly (jack stands). Clean the calipers off with brake cleaner. You can sand blast them for the best results, or you can sand them. That is a little more complicated and time consuming. Prime the caliper with self etching primer and then get your favorite color of spray paint and spray away. Cover the rotors, pads, and sliders for the calipers. Clear coat them with wheel clear coat so they are more resistant to chemicals and brake dust.

 

or just wire brush and paint with this stuff

http://cgi.ebay.co.uk/BRAND-NEW-Hamm...QQcmdZViewItem

 

The calipers themselves don't get that hot. So you can really use what ever paint you want.