The above suggestions are correct.  There will be a 4 pin Deutsch connector under the right hand dash that you can tee into.  Also, I ran into a similar situation where the greenstar "aftermarket" greenstar harness was not wired to the battery and was powering the ISO high current circuits through the 3 pin amp power connector that plugged into the rear right hand console (8420 tractor).  So, if you get it hooked up and it still doesn't show up on the VT, check your power supply on the greenstar harness.