[legodude]

The pinout is on page 4-100 of the Hardware Developer's Handbook Release 2.0:

Notice that not all of the pins pair up, and there doesn't seem to be a ground pin for power return.

(In case it's not obvious, the pairs of pins labeled "X" and "X_RET" are to be connected to twisted pairs inside the cable. This reduces crosstalk.)

Thanks. I also found this on Ian's site which answers all of my questions:
http://www.sgidepot.co.uk/pinouts.html

His idea of using two Indycam cable is probably cheapest.