I may be late to the game, but I ran across your thread while looking for the very same information. Well, after searching Google and the obvious places (2CPU, SGI, Acer), I went back and had yet another long, hard look at the motherboard silkscreen.
Check the lower left-hand corner of the motherboard. The silkscreen in this area has the pinout for connector CN6, which is way up near the opposite (upper right) corner...near the "L" notch in the board. I imagine this is all the information you'd need to get started.
Best regards,
Floyd