I rebuilt a set of SPD's, differrent model (M747). My LBS loaned me the tool to open the bearings, but you probably could improvise. If you can service cup and cone bearings you can do this. I didn't use any special tools for the lock nuts, I was able to get something on the race while I tightened the locknut, can't remember what it was, but some common tool.
I googled up a re-build tutorial, but you're talking basic cup and cones here.