I just went and looked at my rear caliper setup. It appears that you could remove the old pads by pulling the pins as you have suggested. The problem you are going to run into is installing the new pads, as they will be much thicker than your old, worn out pads. This means you will have to push the pistons back into the caliper, there are pistons on both sides. If you stick a prybar in there and use the rotor for leverage to push those pistons back in you will warp your rear rotor. Therefore the best way to do it is to remove the caliper and push the pistons in using the proper tool. I'm not going to tell you what to do here but if you were to crack the bleeder open a touch and very carefully apply pressure to both inner and outer pistons at the same time I would think you would be OK...Just remeber that rear rotor is very thin and it won't take much to warp it. If you do this have some brake cleaner handy to wash off the brake fluid and be sure to top off the master cylinder...