Inverse Heat Conduction to find thermal conductivity

Hello everybody. I'm a Comsol user (basic level) and I want to obtain numerically the thermal conductivity of a material, knowing boundary heat flux and temperature values in several points. I've read other discussion about it but I can't really find how I have to do. I've read about several possibilities:
1. Optimization module (I haven't it);
2. Definition of a weak function containing the difference between measured values and numerical solution of temperature;
3. Implementation of algorithm in Matlab.

What is the best one?
I can open Comsol file with Matlab but I don't know how to move inside the script.
Could someone be more precise in explaining possibility 2 and 3?

Thanks for your help,

Giovanni