I rub Vitamin E and food grade flax seed oil on my corns about once a shed cycle, now more for general skin and internal health than for problem shedding, although that's why I started it.
I found that a daily bath [except for 48 hours after feeding] for about 5 to 10 minutes actually did more to solve shedding problems than even the Vitamin E and flax seed oil rubs. See details of how I give my snakes a bath under the recent post "Impacted?". Humidity control of the tank never works as well as 5 baths a week for my corns and other snakes--remember that all snakes [except desert species] are semi-aquatic.
I also inject my own mix of a moderate dose of Reptisol into the feeder mice I give my corns [it's not absolutely necessary].
What Jim said about oil soluble vitamins accumulating in the body tissues is correct--but the levels of Vitamin E to reach toxicity would be extremely high, and I don't think that it is possible to reach these levels with topical applications of Vitamin E. [Toxic levels of Vitamin A, D and K are very easy to reach, however, and so any supplementation of these orally should be in moderation.]
I'm not sure of what the analysis of jojoba oil is, or whether or not it's safe to be taken internally, so I would be a little more concerned with systemic absorption of that from the skin if you use a lot. [A little is no doubt OK, since it's approved for hand lotion on humans.] This is why I use an oil which can also be taken internally--food grade flax seed oil, which is loaded with the essential fatty acids linoleic and linolenic acid.
Snakes with oh-so-soft skin slithering around my arm,
Doctor Mike