I got a piece of 3/4-16 allthread and cut off a chunk about 6" long. I got three matching bolts and a couple of heavy duty washers. I thread the rod all the way into the hub, then slide on the balancer. Next I install the washer and the first bolt and run it down till it contacts the balancer. Then I thread on the other two bolts just onto the end of the allthread and tighten them hard to each other. Then I use two wrenches, one to hold the crank still on the double-nut deal, and the other to turn against the balancer until it's fully installed. The whole tool cost me maybe $20.
If this is clear as mud let me know, I can get a photo if needed.