FWIW, my friend just blacked out the chrome spare wheel on his Suzuki Sidekick with a spray can of Plasti-Dip and it came out pretty good. I'm thinking of doing the same thing to my rims. I'm sure it will take a little masking to keep the spokes clean and the first tire lever of the next tire change will gouge it BUT it's an easy, cheap, and reversible way to get a little more black.
Scott