Dampen a washcloth and put the snake and washcloth into a pillow case. Tie the pillow case end, so the snake can't get out. Leave the snake inside the pillow case for about an hour and check on him. If the shed hasn't been removed keep trying for another hour. I'd say for up to maybe 6 hours. That's as long as the snake is warmed.

REMEMBER to keep the snake warm. If you can fit the pillowcase inside his enclosure, that would be great. If not, find a place that will keep him warm.
If you use a CHE to heat the enclosure, make sure the pillow case doesn't get too warm and possible catch on fire.

Good Luck!
Jim Smith