This afternoon I went down to the local tool rental place to see about
renting a hammer drill. They have one that's considerably larger than the
ones recommended here (e.g. http://tinyurl.com/33zcrr) for rent for US$60
per day. I showed the guy a printout of the nut driver adapter
(http://tinyurl.com/2bohkg) and asked where I could get one, and he looked
at me like I was from Mars.

So, I'm looking for a nut driver adapter... went to Home Depot and they
told me where to try and I'll call them tomorrow.

I'll tell you, though, even the big rental unit sure doesn't look like
it's up to this job, to say nothing of the much smaller ones at Home
Depot. I'm fairly good sized (6 ft 2 in and 230 lhs) and using a standard
sized two-handed sledge hammer I can't move this rod more than a tenth of
an inch, at most, per strike. Are you guys sure that a hand-held hammer
drill will do the job?

I guess it's worth $60 plus the cost of the nut driver adapter (if I can
find one) to find out...