Circa 2000, It used to be quite a simple exercise
If you held a current ICAO PPL + Medical you rocked up at the local CASA office and parted with 50 of our Aussie dollars.
In return you got a Special Pilots Licence issued in perpetuity (Issued on the spot
)
This entitled you to fly SE VFR by day <5700KG with the licence validity being contingent to your foreign credentials being current.
A quick search of the CASA website seems to indicate that post Part 61, this seem to be no longer the case
Good luck
BAz