The answer to your question is yes and no.
Fleetwood (the company that runs the transportation) recently bought a bunch of new shuttle busses to replace the Van Hool coaches that they ran into the ground. All of the new shuttle buses that they bought DO have lifts in the rear door.
HOWEVER... there are two catches. First, Fleetwood doesn't have a maintenance facility. They don't take care of thier buses like Disney does, so who knows if the lifts will actually work. The buses are only a year old, so my guess is that they still do. But then again, the buses have been beaten up, so it's anyones guess.
The second catch is that they've started to run the old VanHool coaches again. Some of these coaches do have lifts, but they do not work.
My advice would be to call the hotel, and ask them what the procedure would be. It might just be that you need to call them ahead of time, so that they can make sure that a lift-equipped bus is on that route for that particular day.