After you remove the piston the seal just prys off, it is held on by a tapered dovetail stub on the piston, putting on a new seal it is easier to install a new seal if you warm it up with a hair dryer before putting it on.
I have new compression seals and breach seals if you need them just email me .
Rich.
http://home.comcast.net/~peterdragin/index.html/