I'm working on the same problem. I've got a 96 Maxima and I've tapped into the OBDII port but this does not provide the same info as the Consult port (which is what the $3k Consult machines plugs into).
Can you get any info through your friend about the workings of the Consult port...pinouts, codes, voltages, etc?
I hear its complicated.
Also, one could pay $400 and pickup nProbe which does pretty much the same thing as the Consult device.