the caliper service kit comes with new pistons and seals.
They are the same for all the juicy brakes.
Dont know how easy it is to fit new ones, only tried taking the pistons out. I had a caliper with very stuck pistons, i had to bleed the brakes and push them out that way, as none of the methods mentioned in manual worked, took them out and cleaned them, and never managed to get them back in, almost like the pistons had expanded.
Think fitting new ones should be fairly easy aslong as you make sure the seals are seated correctly.