I wish I could be more help than I'm about to be, but I have a bad memory, and I can't remember what I did. What I can tell you, and why I'm responding, is I asked myself the same thing when I replaced the rear calipers, and after a short time, I figured it out and it was simple. Didn't require three hands or anything.
When you compress the caliper piston to mount the new caliper, don't use a C-Clamp. These calipers twist in and out, so take a large set of o-ring removers or something you can get a good bite on the two notches on the piston and shove down and turn clockwise to turn that piston down into the cylinder. You'll damage the piston just trying to shove it down.
One more thing, if for some reason your new calipers don't fit in the stock brackets by about an 8th of an inch, take a flat file and start filing on the caliper until it fits. I had to do that to both sides when I replaced the calipers to get them to slip into the brackets and its been working great for over a year and 8000 miles.
Hope this helped.