74 brake caliper rebuilding help needed

hi fellas, im trying to rebuild the calipers and its not a major job with just the one seal and the dust boot, but i cant seem to get the dust boot to go in. Is there a trick to it or am i doing it wrong. ive tried to put the boot in first , then put the piston in but the piston doesnt want to go in that way. also ive tried to slip the boot over the piston and install that way but the boot wont seat in to its groove in the caliper body after ive got the piston all the way in. ive fought them for about an hr. and didnt get anywhere. any tips or advice?