Another thing to try is to tighten the remaining lugs to take the pressure off of the lock nut. I'm told that works, but wasn't necessary for me. If you're really concerned about the finish on the lug nuts you could probably use one of those kitchen rubber gripper-thingies (yes, that's the technical term) for getting lids off of jars, cut it and put it inside a slightly larger 12 point than if you were to use the socket alone.
I really didn't have to pound the socket on far and it only took a claw hammer - your mom will never notice