Try soaking him first in a non-airtight plastic box (or with ventilation holes) in warm water for 1/2 or so - put it in the snake's tub/tank to keep him warm. Then try with a warm, wet wash cloth. There is a shed assist tutorial under BP husbandry that goes through this.

What kind of snake is it? Might not be worth it unless it is shed you really should get off like eye caps, heat pits, nostrils....

Good luck.

PS Should this be moved to another place on the site?