Upgrading/adding Temp display to Rear View mirror

[Diamondwulf]

So in my LS I have wiring in the roof for rear hvac controls, though I don't have the center stack on the roof and I don't have the sun visors with the vanity lights so I will have to either pull the wire harness for the sun visors and mirror from a vehicle at pick n pull or make my own. The only problem is that the harness connects to a main harness under the dash at the fire wall behind the gauge cluster above the steering column.