If you know any real estate people down there, maybe they have a publication with lists that they have the ability to just go and try to sell since the taxes are delinquent.
Here's some AU thing on Adverse Possession: http://www.mulr.com.au/issues/35_3/35_3_3.pdf
Here's some AU thing on Adverse Possession: http://www.mulr.com.au/issues/35_3/35_3_3.pdf