I treat my rims (clearcoated Style 66) the same way I treat the body of the car. They're both painted and clearcoated. I wouldn't use any chemical sprays on the rims since I wouldn't use those sprays on the body. I use a cheap $1 MF scrubbing pad (with the mesh net on one side) and scrub the rims with car wash soap before I wash the car. When I apply sealant (Klasse) on the car, I do the rims also. Carnauba wax simply won't last as the rims are subjected to high temperatures.
If you wash the rims as often as the whole car the brake dust would simply wash of after a few scrubs and you won't need any chemical sprays to clean it. Brake dust itself turns acidic after a while and then discolors the cleacoat if it stays on the rims.
2003 E39 354 Titansilber Metallic 530i
N6SW Schwarz Montana Leder
M Executive Package
BMW AG Sport Package