I just installed my mpguino to my winter car (1994 renault with efi) and I did not find any vss signal generator from it. It has a mechanical speedo.
So I took my old bicycle "computer" which has the magnet and pickup to count the wheel rotations and crawled under my car.
I attached the magnet to the driveshaft with "tie straps or whatever you call them?" and the pickup sensor close to the magnet so that it can sense the magnet.
The sensor has two wires. The other I connected to a fused +12V source and the other wire to the mpguino vss connection.
This setup was quite easy and it gives very accurate readings.