The way I see it is yo uhave to control the unknown entities. When I let my kids (1.5 and 4) "handle" my corn snake, this means controlling the kids. The young one in particular I have to hold his hand, and keep my finger on his fingers to keep him from grasping or hitting while I help him pet it very gently. The four year old, I have to keep my hands very near in case she does anything sudden, but she gets to hold her in both hands if the snake is in a lethargic mood. If the snake is active, I let it crawl over her hands while I control the snake.
Whenever I go to the reptile zoo, and they bring out snakes for handling, they are always very careful to control the head of any snakes the public gets to touch or handle. The snake is more the unknown quantity in this case.
I dont know the maturity level of the kids you'll be dealing with, or the temperment of the snake, but I suspect you'll need to be in control of both, which may be a two person job.