Success! Following your advice, I identified the 5v and 0v, there were 2 pins for 5V and 5 pins for 0V. Looking at the way the keyboard and mouse operates, I read the clock and data have pullup resistors, and I figured they would use the same value for each; so I went along each pin and just 2 read 1K to the 5V rail, the others in the meg. range.
So, I went for broke and connected an AT keyboard. First time it didnt work, so I swapped clock and data, and it worked! Thanks all.