From all I could find, everyone seems to calibrate their GM sensor used for IAT using the `Calibrate Thermistor Tables` dialog. The problem I see is that this only uses a 3 point calibration curve.
In the Generic Sensors dialog, if you enable the GM Sensor preset calibration it is my understanding this uses a many-point calibration curve built into the firmware.

Am I correct in both statements?

If so, is it possible to use the more robust calibration for the IAT sensor also?

I have noticed that at certain temperatures my GM IAT sensor does not read as close to real as all others (with car stopped over several days at stable indoor temperature, GM oil temp and OEM Water temp sensors both read the same value, but GM IAT is off usually by <1 degC)

 

Look at the corrections that depend on IAT and decide if being off by 1*C changes anything enough to warrant concern. Especially consider this knowing that all those factors will be custom tuned anyway.

 

It doesn't matter that much due to EGO (well except the part EGO resets to 100% when some types of AE or Overrun are triggered, but this is being worked on).
But if the total effort involved in this is something like:
- Add the input used for IAT into the Generic Sensors page with GM Tables
- Configure the Generic Sensor channel used as IAT sensor

Then it's worth it due to low effort. Though, I don't know if that is possible easily as I cannot seem to figure out which input is used for IAT in tunerstudio