You can get a plastic container, put some holes in it for ventilation, get some sphagnum moss, any nursery or home depot type place should have, put some moss in the container, put water in the container so that the moss is wet but not so much that the snake has to swim. You want his body wet, and the moss will help that and also give him something to rub the dead skin off on. Place the container back in the cage, in case he gets out, on the warm side of the cage. You can leave him there overnight if you need to and by then the skin should have either come off or be loose enough for you to take it off yourself.

Sounds complicated but it isn't.