Universal's been getting really weird about issuing their "Attraction Assistance Pass" lately, and the common thought is because people abuse it during Halloween Horror Nights to avoid buying Express Pass for the haunted houses. Lots of people have been getting denied even when they'd used the pass previously. I expect it to go back to semi-normal after
HHN ends, though. I just bring my old one back time after time and they don't really bug me too much about it.
They do use a similar process - you explain what your needs are and how/why those needs make it more difficult for you to use the standard queues. You're issued a paper card that folds up. On the back, a Team Member writes the valid dates, the guest name, and the number in the party. There's also a box they can check for whether or not you need alternative routes when stairs are involved.
Obtaining return times is fairly simple. You unfold the card and approach a Team Member outside an attraction - generally the one manning the Express queue. If the posted wait time is less than 30 minutes, you'll likely be instructed to simply enter the Express queue. There's a barcode on the back of the assistance pass that they'll scan like it was an Express pass.
If it's longer, they write the attraction name, your arrival time, the current posted wait, and your return time on the unfolded part of the card. When you return at that time, they initial the line to validate it. You can't receive a new return time until your previous one has been validated without having it crossed out (and effectively cancelled).