I've worked on several of these and many non-K brakes as well. It can be done w/o splitting the caliper.
Compressed air is very handy for removing the pistons from any caliper. You might, depending on whether they're frozen or not, be able to pull the pistons out with a pair of channel locks but you'll risk damaging the pistons. Remove the dust cover first. Still, if the piston(s) are not frozen, that could work. If you're planning on replacing the pistons--not a bad idea--it probably doesn't matter.
You don't need any special tool to re-insert the pistons. Put some [clean] brake fluid on them and push them in--strait. On these calipers you should be able to push them in by hand but on larger calipers I've used a C-clamp to re-seat them.
Tom