I like to avoid misting the actual snake, and just mist the inside of the cage; misting directly makes them recoil and it has to be stressful. I like to humidify the whole cage for shed times; not soaking it per se, but just moistening the newspaper substrate, the tub walls, etc.
If your snake has already started shedding but pieces remain, a nice warm soak, with some help from you, should get it off. If it remains on the eyes, this is bad.. how are the eyes?