I tried my hand at this little project last night. Did this successfully on a TP and Diamond back cover. TP back cover is now black (and looks sweeet) and Diamond is orange. Both turned out VERY well. You can't tell one bit that they didn't come from the factory this way. It’s almost like a magic trick or something... Steps are listed several times here, but just to throw my confirmed steps out there:
1) Got the RIT at walmart. Orange and Black (one per phone back)
2) Got a medium size pot and filled with water 3/4 way to top.
3) I put my burner on just above medium. JUST b4 it started to boil I added the RIT (full bag) and stirred about 2 min to make sure powder was dissolved. 4) Washed back with soap very good to get dirt and fingerprints/oil off.
5) Just dropped cover in the water
6) Waited 15 min stirring nearly constantly but slow (not sure if that is needed, but did it anyway) I also made sure not to scrap my cover on the bottom or sides of the pot
7) Took out and washed with luke warm water until the water was clean coming off
Dried with paper towel and used a cloth to lightly buff.
POOF - just like everyone else confirmed before me - turned out great.
To those who decide to do this, you won't be disappointed.