Just got back. At the Grand Canyon, we told the person at the entrance gate that we wanted to get the Golden Access card and she had some paperwork right there for me to sign. It was quick and easy. I brought my copy of the doctor's form that I'd sent in to get my parking hang tag since it states my permanent disability w/his signature, but she didn't want to see it when i offered it. She gave us a plastic card with a swipe strip on it and we showed that when we re-entered GC and at other places on our trip.
Nice thing about GC is that there are also "windshield views" where you can pull your car right up and not have to get out if you can't (although the views were better if you did). To do this, you first needed to stop by the visitor's center and get a special pass and gate code to drive your car through a route that is prohibited to most cars during the months that they offer bus service.
dj
p.s. for anyone planning to visit GC -- we went in on our first day at about 9:20 a.m. and zipped right through to the toll booths. decided to exit to grab lunch, but that was a BIG mistake. the line of cars to get into the park at about 12:30 was over 2 miles long--all the way back up to the nearby town where our hotel was! the hotel deskclerk said that at that time of day it could take an hour or more to get into the park, so we opted to take a swim and go back in at 3:00, when she said the line would be smaller. it only took 20 minutes to get in at that time. this was spring break week, so crowds were bigger that usual, but she thought the line was big in the summer, too. if only we'd known, we'd have eaten inside the park....