I have copied this from cjoffroad, never tired it but guys say it works. The Early 2 wire VSS is a simple mechanical switch, it makes and breaks a set of contacts internally using magnets and a reed switch. One wire is from the PCM which has a 5 volt reference internally, the other is the sensor return. When the 5 volts drops to ground, the PCM senses a trigger.
The later 3 wire VSS uses a Hall effects switch to make and break the connection between the sensor return wire and the ground wire. The 3rd wire is a 5-8 volt power supply to operate the hall effect sensor.
The 3 wire sensor colors are usually:
Wt/Bk = 5-8v supply
Wt/Or = Sensor return (signal to PCM)
Bk/LB = Common sensor Ground
With the 2 wire sensors, just connect the 2 wires to the Bk/LB and Wt/Or wires from the harness, you can disregard the Wt/Bk = 5-8v supply wire, it's not needed! It doesn't even matter which wire you connect to which pin on the 2 wire VSS, (but if the colors match, connect them!)
Hope this helps!