Sounds like a fine thing to do. And it'll look sweet for a long time once you've done it properly.
-First step, take your time.
-You'll want to sand everything to be painted with a very fine grit sandpaper. Be as thorough with this as possible to maximize paint adherence. Avoid sanding parts you don't want painted. Cover them to protect them best.
-Clean everything with soapy water. Do not touch anything to be painted after this step. Wear gloves.
-Mask everything you don't want painted with blue painters tape. Use small scissors and hobby precision knives to do detail spots like around spokes. Make sure the tape is firmly stuck to every surface to be protected.
-Choose appropriate primers, paints, and clear coatings for the desired purpose. Automotive is probably a safe bet and can be found at just about any hardware or auto store.
-Spray on a day with low humidity and above 50 degrees F in a relatively clean place. Wind and dust are bad.
-Spray 2 or three VERY light coats of each primer/paint/clear. Do not spray for full coverage on the first pass. This will create runs and globs that look messy and will chip faster. Space out applications by several minutes each. Some paints are different. READ THE DIRECTIONS on the back of the cans
-Remove tape 12+ hours later but be careful, the paint is still gooey below the surface. It's very easy to scratch even at this point.
-leave out of service for 2 days.
-wax with auto wax to protect and further gloss the hubs new paint. This will make it more dirt resistant and easier to clean later.
Enjoy!
If possible get touch up paint too. You're only going to want to paint this thing fully once in its service life.
