I can't help you with mag wheels, I have spoke wheels on my bike. As long as you got enough patience and time to do it, you will be able to do it. I polished both side covers on my engine, valve covers, breather, front forks, both hubs and I'm not sure if I will do it again for another bike. It's a long process. You just need to take your time and do it the right way.
I'm sure that mags must look very good all polished. Post a pic if you decided to do them.