While this thread seems to be about how to achieve this in Sublime, I would like hear opinions on if this is a great idea or not. Spontaneously it seems interesting and logical idea. But...
when I try to read the code in the rainbow coloured samples I find them slightly hurtful to my eyes. IMHO you do not always look for every identifier in the code, you look for one. So you select it and every instance of that gets highlighted. Much more readable (to me) and we already have it in our editor. : )