I recently managed to get an entire shed, that had been baked on for weeks, off of a snake (not my snake). You could try using the same method: Wrap the snake in a moist flannel/towel for a few hours and try again. If it still won't come off, lather the animal in PURE, UNPERFUMED soap and wrap again for a few more hours. You should find that the shed softens and the animal can get it off itself after about a day of such treatments. I rinsed all the soap off after the snake shed, and it didn't suffer any ill effects from using the soap. I used this method with a tropical snake, don't think i'd recommend it for a desert snake though, because of the risk of RI