How to use external temperature sensor with aqara SRTS-A01 TRV

I use aqara E1 TRVs since last year. It is a great device. One of the feature I appreciate most is the capability to use an external Thermometer to sense the room temperature. Until now I used a NR flow to update the sensor_temp attribute of the device. It works well, of course.
Neverthless I found a reference that coud be a smart alternative: let z2m manage the temp updates via an extension. I still did not try it, nevethless it sounds promising:

the only drawback I can see is that you need to hard code the device network id. If you change it you have to chenge the extension.

EDIT: … where I have to put the extension? I cannot see any extension directory in CORE z2m…