Calling an outside script

Hi all!
I'm starting a new project in COMSOL (I'm quite new to the program). The thing is, I have a fortran routine that solves a radiation exchange progress between surfaces quite in an efficient way. So, I would like to have this exchange process as a boundary condition for an induction heating problem.

The thing is that this boundary condition is temperature-dependent (not only of the local element but also from all others, since it's a closed cavity), so this boundary condition should be updated in every thermal iteration.

Is there a way for doing it just from inside COMSOL? The Fortran program can generate an ASCII output with some values that can be read by comsol and then update the boundary...

I'm guessing that perhaps with the Matlab integration it could be "easier" to implement, but I'm completely lost as where to start looking.

Thanks in advance!

P.S.: I'm posting this message as a 3.5a question, but I'm changing to 4.2 during next month, so replies to instructions in any of the two versions is welcome.