I've wired my car for gauges. What you need to do is drill a hole in the fire wall on the driver's side, if its small and done right you won't notice it.

Then route the wire through the lower air vent on the center console (there's a space for it). This will route through to the other vent. You then need to remove the glove box and route the wire behind that and up through the space on the passenger side between the dash board, window, and a pillar. From there just secure the wire down along the window and you won't see anything.

This is the only feasible way I have found with out ripping out too much or drilling holes. I'll see if I can get some pics up.

Also what kind of sensor comes with the Air Temp sensor? And where would you mount it?