Thanks very much to everyone who responded. I got the problem solved
with much less hassle than I anticipated.

I had based by thoughts on how to get to the connection of the cable
to the keel on the descriptions of the owner of the boat. Turns out
that was a mistake.

I did not have to cut off the top of the centerboard trunk as was
suggested. There was a piece that simply unscrewed and gave complete
access to the top of the keel and the entire system.

I found that the cable does, surprisingly, attach to the upper/aft end
of the keel. It goes like this: The end of the cable goes through a
hole in the mast compression post and is pinned with a bolt. The
cable runs aft to a block attached to the keel. It makes a 180 degree
turn and then run forward to a sheeve (sp?) also in the forward side
of the mast compression post. The cable makes another 180 degree turn
around the sheeve and heads aft through a hole in the top of the
centerboard trunk to a winch on the aft end of the trunk. Did that
make sense?

The point is, the entire apparatus is accessible from the cabin (with
the keel up).

Local folks have recommended using a galvanized steel cable designed
for a trailer winch rather than trying to use stainless steel.
Besides the significant difference in cost, the galvanized steel will
wind on the winch easier without breaking. Since we are sailing in
fresh water, the galvanized probably will last for many years without
rusting. What do you all think?

Lee Huddleston