I'm not actually positive, as I was always able to pull Lily out of her attempts, but my guesses would be a heated incubator along with supplemental care to keep systems functioning while they try to get past the attempt - subcutaneous injections of fluids (or an IV?), etc. I know from wildlife rescue volunteering that injection of warm fluids is usually a good way to help get the animal warming up from the inside as well as being in a warm environment, so I wonder if that might be an option that vets would try with a hedgie stuck in a hibernation attempt.
~*~*~ Kelsey ~*~*~
RIP my sweet Lily ~ 6/12/08 - 1/20/12