Looking at the wiring diagrams (the sucky one that I have from the Haynes manual and the online FSM, which sucks because you can't save the PDFs to a file, and you can't print, rotate, or zoom) it looks like there is a red/yel wire going into the cluster that is labeled A/B LED. This wire is hot in RUN and START, so this is probably the feed for the LEDS. The problem is that from what I can see on all of the lighting diagrams, it looks like the actual switching of the LED color that occurs when you turn the lights on (presumably from the PARK light circuit) is communicated to the cluster through the CAN bus. It looks as if the park light signal is converted to CAN data in the low current board inside the smart junction box, and that signal is decoded within the cluster. If this is the case, then disabling the green LEDS would be very difficult without dissasembly and reverse engineering of the cluster itself.
Also, IMHO, I wouldn't go poking aroung the cluster wiring with a test light or a meter too much.....if you feed 12V or a ground directly into the CAN bus wires you'll be buying a new cluster and/orsmart junction box or ECU.