I did mine about 4 years ago. I think the stripper used was "aircraft paint stripper" from WalMart. It took a couple or three applications to get it all off for me, some have had an easier time of it.
I only stripped the smooth parts of the rims, not the rough cast part (which is much harder to strip chemically and doesn't polish up to a shine). Some have masked the rims, but most don't. Since the paint is difficult to remove from the rough, you can easily strip them just by putting the stripper on with a paint brush. (Be sure to wear gloves that the stripper won't eat, this stuff is toxic! ) Final traces will have to be removed with fine steel or aluminum wool and/or fine Scothbrite pads. Once all the paint is off, they can be shined up with most any metal polish. Nevrdull, Mothers, Magic Metal Mix are popular ones.