[Beav]

Uh, the o-ring goes in the bore first, then the boot followed by the piston. One other way, usually a bit more awkward but sometimes handier, is to insert the o-ring, place the boot just on the lower edge of the piston and then try to get the boot lip into its groove in the caliper followed by pushing the boot and piston home. Normally the boot doesn't seat completely when doing it this way, but if you're like me abd have large fingers trying to work in small holes it could be the only alternative.

When working with multiple bores place both o-rings in position and one piston without a boot in one bore - that will contain the air while working with the other boot and piston. You may have to use something to retain the incomplete piston and be careful with the air - blood blisters (broken fingers? doubtful) are easy if you get crazy and allow the piston to pinch you. After the first piston/boot is in retain it and use the air to pop the incomplete back out (place a rag or someting between the piston and caliper to cushion it when it pops out.)s