I did find some information on the Frontier forum.

Scangauge 3
In anticipation of some towing and wanting to avoid a fried transmission I picked up a Scangauge 3. I was able to get coolant temp, engine oil temp, transmission temp, and air intake temp easily. Unfortunately the TPMS codes I'd gotten some years ago were apparently not applicable to the 2015...

ScanGauge II Owners - How are you using your Gauge?
So, I just received and quickly installed (just ran the cable under the floor mat temporarily) my ScanGauge II - purchased as I want to monitor my transmissions temps while towing. Setup both Transmission Temp 1 and 2 (not sure what the difference is yet or if only one or the other...
I'll try it today but doesn't look like it will work. Bummer.