This can be tricky - some patients and PTs never really feel that they can 'get it right'. Bio feedback is helpful but I think it is moe useful to practise in isolation first. The person has to understand the theory and then increase awareness of TA and MF. If they are unsuccessful in this after trying hard, I would abandon movements in isolation and go for the swiss ball.
Incidentally, I am trying to teach martial arts instructor a) costal breathing and b)TA facilitation. Not going to be a success, I feel.