:idea: Baking soda and vinegar. It will foam like crazy, but it wont hurt him. I would powder him with the baking soda, rubbing it in well, and then mist him down with vinegar. Towel him off, and brush the remainder out as he dries. If you have a blower, even better- but even a high speed hair dryer (low or no heat) will help get any powder out. It wont hurt him if he eats some- he may even like the salt content.
:!: Disclaimer: I have never tried the above before and have no idea if it will work. But it is what came to mind, so there ya go.
:idea: Hydrogen peroxide. You'll probably need 6% for a bleaching effect though.
:idea: Lemon juice and direct sunlight.
If all else fails, pray that he sheds soon!