Although it will look horrible, a few painting tips I have for you, since I've done this to stock EG si/EX wheel covers.
Make sure you sand them well to get the factory coating off, then prime them with self-etching primer. Then wet sand. Then spray them evenly with any color you like, then get a mild to low gloss clear coat to seal them up.. MAKE SURE you let them sit for a few days, or else rocks will indent the paint and it will look goofy. Trust me, I had to redo mine because I only let the paint cure for a few hours.