> Has anyone used another method of disabling the engine other than that one
> wire?

I have a fuel pump switch in my '81--installed for a
reason other than theft.  I got into the FP wire
at the FP relay, front, left of the engine
compartment and ran wires to a switch mounted under
the driver's seat:
http://jones.colorado.edu/jones/VW/VWfuelpumpswitch.jpg
(The other two switches control the cold start valve....)

Richard