Hi Bruce,
I have the cable, but not the Mexican adapter. The Vag-Com cable is basically a replacement for Volkswagen's 1552 diagnostics tool, for which your car uses the 3-prong Mexican plug. There are a few options...
1) you buy the mexican adapter from ross-tech's Espanol site, and the 2x2 adapter (also needed) from the American site...this is rather expensive.
2) We find a wrecked modern VW/Audi and make our own adapter...The interface to your car requires +ve, -ve and the K-line from my cable which we can _easily_ determine with a wiring harness from the donor car. The donor car is simply donating the female connector to match my cable. We will then need to make a 3-prong end for your car, but that's not too difficult.
-Dave