I used a product called Custom Wrap by Dupli-Color. It's the equivalent of a better-known product called Plasti-Dip. You spray it on, and it peels or wipes off when you want it to (assuming you did it right).
Started with some serious cleaning of the wheels. I used Simple Green mixed with water, a sponge, and a lot of elbow grease. I chose to remove the wheels for application, but that is not expressly necessary. In my case I didn't want to worry about over-spray onto the car or rotors, and felt I could do a better job of getting all the nooks and crannies. I didn't mask anything at all; I just made sure to do lots of (4-5) coats on everything (including the tires) so it would peel nicely off. The whole wheels job used 2 cans. I put the wheels on top of an old tarp before spraying, because I heard this stuff does not come off of concrete or asphalt. When I was done, I put the wheels on the car and drove it 100+ miles. After that, most of the over-spray onto the tires was gone, and the rest peeled off easily. I am the king of laziness.
I took a little more care here and made a basic mask out of cardboard and masking tape. I don't have any photos, but on each I basically sprayed the entire emblem plus a box about 1-2" around them. After it dried I peeled off all of the parts I didn't want blacked out. On the front emblem, I just changed the inner bowtie from gold to black (why does Chevy still insist on having gold logos on a chrome grill?) On the back, I left it fully blacked out so it basically disappears into the black part of the trunk around it.
I am pretty happy with how all this came out. Time will tell as far as how long it lasts, but I hear it becomes pretty stable after one week - you can even take it through a touch car wash with no anxiety.