Ok all you tahoe owners. Maybe you can help me out.

I have a 2007 Suburban in which I recently installed a factory nav. I ordered and received the JP Customs VSS kit and will be installing that shortly in order to combat the nav systems failure to respond to being off course. However, I would like to hook up the voice recognition but I seem to be reading conflicting threads. Do I need a plug with three wiresfor the back of the OnStar box or do I just need to tie into a couple of the wires (grey and blue, I believe) that are already plugged in as seen in another thread (https://chevroletforum.com/m_15129/tm.htm)? Also, does anyone know what the various pins are for in the OnStar module? Thanks!