[timothy]

I swap brake pads quite often (track and street); here's the method that works for me. Quite a few use a c-clamp but I've never been a big fan of that approach.
1. Put the old pads back in the caliper
2. Position a set of slip joint pliers in the space above the rotor and between the pads so the jaws touch the tab at the top of each pad.
3. Pull apart on the pliers handles. As the jaws separate they push outward on the pads and pistons are forced back into the calipers.
4. Remove the old pads and insert the new.
5. Reinstall retaining hardware