I do this all the time. Two wires go out to the passenger area, breaking out of the harness where the turn flasher can wires break out. One of those wires goes back to the area where the 5 prong heater switch resides; the other goes out past the firewall grommet for the clutch compressor. A fifth wire is added to the heater switch connector with a short segment. The bitch is routing the wire through the firewall grommet. There's no choice other than to cut the wire and fish the wire through the grommet, leaving the large female bullet in the engine compartment side. Fishing the wire through the grommet is no easy task. Once done, you'll have to splice the cut wires back together.
Be forewarned: it appears that the heater box wires are re-located in the harness from the non-AC version to the AC version, but electrically, they are identical.
