Yes, that's correct. Boundary Conditions (BC's) can be adjusted by IFM implemented parameters. Carlos already addressed this topic in a generalized manner: http://forum.mikepoweredbydhi.com/index.php?topic=2047.0. The material file with the extension *.fpi is the file which must contain the BC.
At the moment the implementation in C/C++ is easier than in Python. The reason is that compiled C/C++ code can be attached to the fem problem. In contrast, a Python script can not be attached to fem-files. Instead, you load the FEFLOW kernel as a module, while the Python script needs be called from the [b]run_model.dat[/b] file.
The next FEFLOW 7.1 release allows you to attach Python scripts to fem-files.