I use a high speed rotary buffer with a hard cotton bob on the end with a good dedicated aluminum polish. The one that I like is Zephyr Pro-40
The method that I used was to get the surface as clean as possible...add some pro-40 to the rim and hit it with the buffer at 2100 RPM's....heat is the key to getting the aluminium to polish out and take the little scratches out and anything else that is in the way....The rim that I posted was real bad there was no shine at all from winters rides to the snow country...This took me about 5 hours to do all four....I then used a sealant on it to help them from tarnishing again.
I should also add that get ready to have everything turn black...I cleaned the cotton bob by soaking in hot water with Oxy-clean and extractor soap over night...Rince really well in warm water and let dry for the next time
Here is a link to the web site where they are available and the polish as well