When we took the Undiscovered Futureworld tour, the tour guide told us that if there is a medical need, such as for someone someone who is claustrophobic and in a wheelchair or
ECV, it is possible to use the back entrance. Apparently you should be able to ask a CM, it might take a little while to get someone to take you though.
I have never had a need to use this entrance, so I do not know how accurate this statement is, it is just what we were told.
You do get to use the back entrance to Soarin' on the tour and there are height checks available there, so they obviously use it somewhat routinely, which make me tend to believe the tour guide.