Wow!
Fraser - yes, it's in the engine compartment.  I may have to do the manual drain like was suggested by ljkrume with the notched tube.
jrevens - I hadn't considered the push-type valve and that would suit me well.  I wouldn't mind crawling around under the engine to push a tube up against a push valve - it seems like it would be easier.  I have to replace that existing push&turn valve anyway.
After all these good suggestions, I think I'll skip trying to hook up that cable to the gascolator and just replace the little valve on the bottom of the gascolator with a push-type valve that has a little pipe nipple below it and I'll use ljkrume's tube idea to drain the fuel into a bottle where I can check for water.  I think that's better than the old' Cessna habit of just pulling on the cable and letting the plane "pee" on the ground where you don't have a chance to check for water.
This is an excellent forum, guys, and I appreciate all the help.  The education for me from this one thread is:  1) a simpler set up with less parts to go wrong or maintain, 2) less risk than what I was considering because of some sort of lever connected to the cable that could encourage leaking, 3) I would actually be able to see the water in the fuel, 4) less weight by eliminating the unused cable, and 5) less cost because I only buy a little valve that needs replaced anyway.  I still don't know how Cessna engineered it, but I'm going to our Chapter meeting on Friday and I'm going to take a peek.
Rich - you probably didn't want that sock back anyway!
jrevens - are the valves in the link below what you had in mind?
http://www.aircraftspruce.com/menus/ep/ ... afair.html