I do not recall a rear-brake specific link, but it is a partial removal of the rear wheel. If you are considering doing any rear maintenance (drive spline lube, etc) just do it at the same time. Otherwise if memory serves (a lot easier when actually looking at it) you will need to remove the left bag, left lower shock bolt. I think you can remove the caliper assembly from that point by its bolts, but I have always just done it when I had the wheel off for another reason.
The pad replacement is vey much like the fronts, and there are tutorials on here for that I believe. When you first hit the website, there is a 'bikers workshop' link. Go there.
The brake pad pins are held with a pin keeper held by a short bolt, 10mm socket to remove. Then drive out the 2 pins as you push down on the bottom of the pads to lessen the spring pressure on the pads to pins.
This is rebuilding an 1100 rear caliper which is very similar to the 1500 rear caliper. They use the same pad style and you will see the steps to remove the pads. http://goldwingdocs.com/forum/viewtopic.php?f=11&t=56
I would highly recommend that you rebuild the rear caliper while you are there
I am in the process of doing all mine; got the fronts apart and then found that not only did I need the seals, but also needed the pistons as well. Guess what I had to wait on parts for??? Highly recommend you have the seals and pistons on hand and change them regardless. When I ordered up the front pistons, I got the rears as well, don't want to be waiting again. Any age on the bike and they will be corroded and pitted, time for new, its your safety.
I've rebuilt the calipers on several 1100s and my 1500. I never ran into unuseable pistons. Light pitting isn't real problem in the caliper bore since the pistons and cylinder don't actually touch each other as they ride in the seal and dust seal. Piston pitting would have to be pretty advanced to cause leaking.
One very important part of working the calipers is to make sure they aren't frozen in their mounts. Since there are only pistons on one side the caliper itself has to be able to move outward to bring the inside pad to bear on the disk. There is a sleeve between the caliper body and the smaller mounting bolt which MUST be free to move in and out of the caliper. Whenever the caliper is off the wheel that sleeve should be checked and cleaned and relubed to prevent the caliper from freezing in place.
One way to see if the caliper is frozen is to look at the pad thickness of the two pads. If one is much thinner than the other, you have a frozen or partially frozen caliper. Normally functioning calipers wear both pads pretty evenly. You can check for a stuck caliper by looking at the ends of the pads, no disassembly needed though a flash light and mirror makes it easier.