While it might be possible, the code does not exist in ArduPilot to support it. And that code has to be there before Mission Planner or QGroundControl can support it.
Contributions to ArduPilot are always welcome so if you want to write the code to support it that would be great. Otherwise you’ll have to wait until one of the developers has enough time to write the code for it. Right now ArduPilot has support for temperature sensing if it is part of another protocol such as a temp sensor on a IMU or baro. But support for external sensors is a different animal.
What you want is already available using more advanced telemetry than Mission Planner. I have all the ArduPilot telemetry on my RC radio plus engine rpm, rotor rpm, engine temperature, Outside Air Temperature, KIAS (kts indicated airspeed) with the use of a FrSky SPASS-70 pitot tube. None of which you can get in Mission Planner, except for the rpm’s.
This is done with advanced telemetry scripting running in the RC. Unlike Mission Planner it has zero latency. Eliminates the need to lug a 1990’s technology Windows laptap around that has a screen that you can’t read in bright sunlight anyway. Can use a more modern mobile device like a tablet or smart phone to upload flight plans to your helicopter with WiFi - no telemetry radios needed.