The ScanGauge cable down to the OBDII connector which I'm guessing is somewhere under the dash or steering wheel?
That OBD2 connector is located between the driver's knees down below. Wiring it up is very simple, but best to have the factory route the cable for you side by side with the monitor cable which they are routing anyway. The cable used is a standard computer internet cable called RJ45. The factory should use one that is 8 feet long. 6 feet cuts it close. You use the special 6 foot ScanGuage-II cable to connect only the last couple inches. This way you can use the SG2 for other vehicles, along with not complicating matters with the factory. I am sure they can do a simple request installing the 8 foot long RJ45 cable side by side with their backup camera cable. Tell them to place a computer internet cable from the OBD2 connector to the center mirror and let it hang one foot at each end for you to finish the job. If you change your mind about a ScanGuage-II, simply tuck the cable behind the headliner. No harm in that.
This is a cheap generic computer internet cable, I recommend 8 feet long.
This is the stock 6 foot ScanGuage-II cable
This is what you use to connect the two cables toegther. The same connection is on both ends of the box.
The SG2 cable stays bundled up, stored behind the driver kick panel. Doing it as I recommend, the factory can buy a generic 8 foot long computer cable and install it without it getting complicated for them. And you have the option to use the SG2 on other vehicles without buying another special SG2 cable.