Transform Dimmer into temperature regulator

Hi! I am a newbie and sorry for asking questions that may be answered elsewhere.

I want to control the temperature level of an old boiler by changing the Resistance of an input to it (by simulating a NTC sensor)
Ideally, I could use a Fibaro/Qubino dimmer(?) to do this by controling a potentiometer (maybe optocoupler, mosfet or other).
Two questions:

  • how can I change the scale from “%” to “degrees Celsius” as viewed in my Vera Plus controller. Reprogramming of dimmer or Vera? Luup programming?
    -Any other z-wave component that you would suggest.