I was at Haunted Mansion last fall with a wheelchair. We still had to go through the graveyard queue, and then through the stretching room before we were pulled aside, went out the exit to park the wheelchair, then back in. It was a lot of transition from dark/light/dark, and more turns than the regular route. We stayed near the wall (instead of moving to the 'dead center' of the stretching room), and then were the last group out of the stretching room, with a CM using a flashlight pointed at the floor to guide us. I don't think that the wheelchair route would help you at all at Haunted Mansion - but a CM should be able to help you find a stable/safe place to stand in the stretching room, and then light your way to the hallway.