Ideally, you would modify the source code of this block to implement such functions. However, the source code of 3-zone pipe is not visible.
One possible workaround to consider: make the external heat transfer coeffcient of the pipe really large, and the wall thickness zero. As such, the thermal resistance from the external convection and wall-conduction is very small. Then implement convective heat transfer block outside the thermal port, together with thermal mass and conductive heat transfer blocks for the pipe wall. You can then modify the source codes of the convective heat transfer block and the conductive heat transfer block to make h and k as inputs (should be just a few lines of Simscape codes). Now, apply the functions you want.
