I haven't heard of anyone doing it, but that's not to say it isn't possible.
It might not even be possible. If there is only a regular light color and the buttons are white I don't think you could, which is what I'm leaning towards.
If it was possible I would say it would require opening up the phone and replacing or painting the actual light. I know I did it on my old dare and had to open up the phone to do it.