There's a fairly cheap tool for SPD pedals of that sort, the TL-PD40.
I got mine from the local shop for a few bucks. Works nicely with a bench vise.
also.. it took me a bit to learn that "overhauling" such a SPD pedal is usually done by pulling the axle assembly, injecting some new grease into the bottom of the body, and reinstalling the axle assembly. The old grease will ooze out around the seal during the axle re-installation.
Steve in Peoria