I picked up some RIT dye for use on my new AT101Ws which should be here in a few days, but I couldn't resist trying them on my Customizer 104 first. I was really worried about how they'd turn out, and if I'd accidentally melt them, because this is my primary keyboard and I'd hate to have screwed it up and had to order new keys from Unicomp.
I took off the F keys, Prt Scrn, Scroll Lock and Pause, along with the top and right hand keys on the number pad. I used one box of brown dye, and put it in a fairly large throwaway pan on my stove mostly full of water with a decent amount of salt, and heated it so that it was steaming.
I washed the keys in soap and water, rinsed them, and let them soak for a minute in rubbing alcohol.
At first, I was getting almost NO results except for some dirty brownish grey keys, but I continued to let them soak through eating dinner and reading through almost the entirety of this thread. I turned up the heat a bit (from 3 to 5 on my stove, goes from Low, 1-9 and High) since the plastic supposedly had a high melting point.
Success. In about 15 minutes I have beautiful, rich dark brown keys that I suspect will look VERY nice on my keyboard with the black frame and grey primary keys. Thinking about doing the alphanumerics in black (Sort of a "Das"-y or Otaku Filco sort of thing, blank keys being the idea) and the rest of the keys in red (WASD in RED too, for gaming pwnage, amirite?).
Just letting them dry now. Only issue is that with the dark brown the text is invisible or VERY hard to read. It varies. Actually, the text on the side of the keycaps (like "Break") show up fine. I think it's the glossy finish on the side.