rebuilds are not difficult. the hardest part would be getting out the pistons but that is easily done with some preparation.
You could do as LostPawn suggested, when I did mine I just pumped the brakes while there was nothing in the caliper to get the pistons to come out a bit. Be careful doing that though, if you pump too much you'll pop the piston out completely and get brake fluid everywhere.
"Give a man a match, and he'll be warm for a minute, but set him on fire, and he'll be warm for the rest of his life."