You enter through the exit, but at one point in the queue there will be a CM to direct you over to the regular queue. They make everyone watch the safety video. After that, as ice stated, before the stairs, there's a gate that you go through. You go up the elevator, cross over the loading area, then down the next elevator. You load from the same side as everyone else. The CM will then take your wheelchair back through the elevators so it will be on the exit side waiting for you.