I took a pair of adjustable channel lock pliers and ground out the back of the jaws, leaving just the first upper and lower ears to grab the notches in the lock ring. Gives solid, adjustable purchase into the notches without the risk of the wrench slipping off, which happens so often with the hook tools. Cheap too, since these pliers can be had everywhere. You can also grind the two ears into semi-circle if you happen to have one of those lock rings with circular notches.
Roger MacPhail, Park City, Utah