i'm pretty doubtful as to the presence of any literature out there.

i've been asked to "treat" a donor in this situation before, where there was some concern about excess secretions and the medical staff involved declared they wanted the lungs in as good condition as possible. they and i both believed that physiotherapy would aid in this.
there is potential risk for introduction of infection into 'clean' lungs. i guess it depends on what the donor's past medical history is and the reason why they are now 'dead'.