I had to replace right rear caliper on my Blazer w/ABS system. Now I can't get the brakes to pump up in order to bleed them.

 

try a one man bleeder kit, they are pretty cheap at the auto parts store

 

I have always found the reverse bleeder to be the easiest to get that firm pedal back, if your not familiar it just has a small hand operated pump which attachs directly to the caliper bleed screw and pushes the air up through the system out the mc.