CanÂ't really help you with the breathing, but thereÂ's an alternative to the setDamage alternative 456820 suggested. Set your loon to:
unit setDamage -1
A negative damage level will not kill the unit, but his hands will start to shake like heÂ's a smoker in need of another Marlborough.
Breathing sounds are quite easy to implement as custom soundfiles (just breathe into your mike during the recording and trigger the sound with the say or playsound command).