I was doing this on a set of bullitts, used some paint stripper (gell type that stays where you brush it) to get rid of the clear on the machined lip (all the way down to the anthracite color), and hand sanded the rash. Ended up being WAAAAY more work than I was willing to put in it, but the one wheel I finished the lip of looked good from a few feet (in close you could tell where it wasn't rounded perfectly and had been sanded down). I ended up using some Mothers polish on that one and it had way more bling than the other 3 wheels and their 10+ year old machined lips, lol. You can do it, but it's a lot of work..
Best way though would be to have it done professionally, but with what these wheels cost new, you'd likely be better off..