I just did my wheels last week, although I didn't powdercoat them.
I was planning on sandblasting them, but the wheel is pretty soft and the body shop that I took the wheels to recommended I not sand blast them, and just hit the wheels with some 180 grit sandpaper instead.
I did, the paint on the wheels from the factory is so thin, even with the 180 grit I was able to take the wheels right down to the metal with minimal effort. I didn't take it down to the metal in all spots, only where I could find scratches.
The sprayed the wheels senna red and put them in the oven to bake the paint on, looks fantastic. Almost flawless, I couldn't be happier with the result. It only took me about 20 minutes to sand each wheel by hand too.
Hope that helps.
David