Using RIT dye, You literally boil some water, use some epson sea salt, dunk the piece deep in the water so the ENTIRE piece is covered, the dye penetrates the piece, I waited about 7 - 10 minutes. I haven't had any problems with discoloration due to the dye.
You will have discoloration, if you have multiple pieces (like R/C car rims) and do them at different times/temperature of water.
Nothing like using dye in your S.O.'s favorite pots and pans
I used her good stainless ones, while she was gone. I cleaned them immediately, and they cleaned up easily. GOOD LUCK!
The dye runs ~$7 - $9 a bottle (WAY too much dye) or ~$4 for some dye in a dry powder form. You will be able to do (literally) hundreds of knobs. I haven't looked to see how much the knobs are so, for the mess and $ you may be better off buying the knobs.
I just thought I would put it out there...
for those of you who don't want to lose your car's "soul".