I have indeed heard of Nicolas Roeg's Walkabout.  This film has
been screened several times at USC as part of an introductory graduate
theory caXXX class.  You m XXXX may want to contact the Norris Theater
staff at USC for info on its distribution as they have rented it in the
past.  Try contacting the Critical Studies office at USC at (213) 740-3334.
They should be able to transfer you to the correct phone number at
Norris Theater (you shouyXXX should probably speak to Dana who is in charge
of operations there).
Best of luck.