The pin arrangement in the ribbon cable socket of the OSMC was not that clear from the accompanying user guide.
I had to do a bit of detective work to understand how to wire the micro to the OSMC.
NOTE: I now (2012) use Sabertooth motor controllers and send data to them via a serial connection from an Arduino.
For those who do want to use an OSMC, here is the wiring diagram I came up with to run it from a hobby robot microcontroller I used to use, based on an ATMega32 chip.
There wasn't a pin diagram like this with the OSMC literature at the time I wrote this.
Here is the pin arrangement I came up with to make the thing work: