Not precisely the same setup, but I used the Vehicle Speed Sensor (VSS) on my '95 transmission to drive a Dakota Digital speedo. The speedo basically just counts pulses, and displays a speed based on the calibration that you set (follow wife's car at steady speed, reporting to one another on cell phones, push calibrate button, and voila!).
I'm not positive that the your trans has the same setup or that your VSS will produce the same usable output, but it seems like it might...