Why don't you just trace the cable back to the power button, or even just see what colour the power button cable is. This way you'll know which pins to short.
It's obviously in a front panel block which will only fit on the board one way.
That would be a lot easier would it not? What's the point of this if I could have done that in the first place?
Just tracing back the wires to the power/reset switch will enable you to find which one is the front panel block.
What do you reckon Coupe?
Would you have marked the pins i did? (They seem the logical choice?..)