I got a quite pale cool dude from a trade a few months ago (I think with Toy Toad), and kept him to the side for a while as he was a bit different.
I found him again, and put him in a little jar of bleach and left him outside for a few weeks. We had some really hot weather (for us!) for a while and was hoping the UV would make it even more white. No idea if the bleach or the sun was working most, but it did go a few shades.
Results are quite good, thought I'd let you all see Jackson