Actually, I found that I could not twist in the piston no matter how much I leaned on the pliers as I was turning them. Then, I realized that I was essentially trying to push all of that brake fluid back up to the top of the reservoir. However, I had just last week installed Speed Bleeders, which allow me to open the bleeder bolts without worrying about air escaping in. So, I opened the speed bleeder, turned the piston in with about 3 easy cranks, then closed the speed bleeder back up. As a bonus, turning in the piston pushed out some of the dirtiest brake fluid inside the caliper. With this trick I saved a bunch of time off of the sweatiest and nastiest part of changing my rear brake pads. The C-clamp, which I had already bought, served very well in holding the pads in place while I installed the anti-rattle spring.
At $7 each (need 6 for all 4 calipers) the speed bleeders have saved me a ton of time and made changing fluids and now pads much easier. I highly recommend them to anyone who will be doing a few track days and wants to stay on top of their brakes.
A