I'm assuming that you mean this thread:
http://www.madabout-kitcars.com/foru...9&postcount=33
So you'll know that the green wire in that three way plug goes to the coil of the main relay and is energised when you turn the ignition on.
I clipped the other two leads, heat shrank them and bound them into the loom when I recovered it. They don't seem to be of any use in the Sportster, and I never managed to decipher the wiring diagrams (Haynes, Bentley or BMW) for those cables.