First, does your crankshaft have a threaded hole in it? If so, puth the balancer on using a bolt in the hole to pull the balancer onto the shaft. If not, and you have good access to the crank end, get a bolt and washer set for balancer retention, one for a sbc v-8 works. Should have a 7/16NF bolt iirc. Drill and tap the crank for the bolt.
Pounding on the balancer shouldn't hurt the balancer, as long as you hit the portion that attaches to the crank. But you do damage the main bearing in the engine that takes the thrust. There is a tool for installing the balancer, but I have never used one.
