[shorod]

Correct, you shouldn't need to pull the boot to get it to screw back in. There is a took kit that works well for compressing this style of rear brake caliper with integrated parking brake feature. The little socket cube that fits on a ratchet wrench is pretty close to worthless since you also need to apply pressure while spinning the piston to get them to compress. The kit is a much better solution. Harbor Freight sells one of the kits and many of the chain auto parts stores will have a similar kit as part of their loan-a-tool program which shouldn't cost you anything as long as you remember to return the tool when you're done with it.

-Rod