That's a tough one. Dye transfer is almost impossible to remove. I don't recommend magic eraser because I had it destroy the handles on a speedy and I had to have them replaced, although some people use it. You could try a baby wipe (non-alcohol). I think there are some threads in the FAQs section about cleaning handles, but I don't know if they deal specifically with denim transfer. I'm so sorry that happened!
I do know that it is almost impossible to remove on patent though.