NB: There's already a project that does this, and includes other countries:
The idea is to create an 'overlay' for Open Street Maps that would show the nations of Australia.
I have no idea how to do this.
As best I can tell the boundaries on the maps are not, and are not able to be(?), perfectly accurate.
Considering that these borders change over time, it's not really possible to make an accurate map.
David R Horton is the author of the AIATSIS map, the latest version is from 1996.