Found some info over at AR15.COM. Looks like I need to center punch the dimples, drill them out, drive out a pin, and remove the old part. Then, screw in the new part, drill a hole through it, drive in a new pin, peen it over, then file everything smooth.
It'd be nice if the manufacturer or the distributor made it clean that the part takes this level of work for proper installation. Oh well, live and learn.