Well, after many trying months, my aftermarket cruise control finally works!  I installed a vacuum storage canister with a check valve and check-tee from a Golf/Jetta.
  I used heat to bend, un-bend and form the molded plastic main vacuum hose/ check-tee assembly.  I grafted this in place of my original straight tee that goes to the front brake booster.
  The storage cannister went nicely into the right rear shelf (in front of the taillight area) and the additional small plastic check valve in-line with the cannister which was tee'd into the line going to the cruise servo.  The cruise servo line was tee'd into the main check-tee, and the second tee connection was plugged with a short hose with a screw in it.  I took it for a test drive and it finally holds!  This made all the difference, as before it would always drop out and failed to hold at any speed.
  Now,  I just need to install the VSS magnet/ sensor on the CV joint (that a listmember graciously supplied!) for a more consistent rolling speed. The coil wire pick-up method is good to prevent engine over-revving, if you have a manual transmission, but mine is an automatic and I won't have that problem.  Sensing coil pulses (engine rpm) does NOT control vehicle speed well for uphills or downhills; about a 15 mph range, which is unacceptable, but better than no cruise at all, I guess.
  The brakelight sense wires kick it off very well, but I've read that dirty bulb sockets or blown bulbs can cause problems.
  This AudioVox CCS-100(?) that I bought NIB off of eBay was missing the VSS sensor assembly (go figure!), but I hadn't picked up on that small fact until about a year later, when I finally went to install the kit.  
  It's nice to finally have functional cruise!

Mike B.