I use SA2 fairly regularly but there's no Australian Statistical Geography Standard (ASGS) support in QGA currently (though we have certainly requested it since way back when QGA was first introduced). Instead I've downloaded the shape files from the ABS site and loaded them via the geoanalytics connector. The shape files are very detailed however so I've typically had to simplify them (again via the GA connector) or make sure that the layer is only visible once a small number of SA2's is possible. Alternatively you can use a tool such as QGIS to simplify the shape files and convert to KML.
Here's a link to pre compiled SA1, SA2, SA3 and SA4 dated 2011 areas from ASGS,
Please review the sample app for usage.
The folder contains copyright and source information.
Note, it is not difficult to create import the areas from source to QVD using the Simplify operation the QGA connector.
The only hurdle is that the ASGS source areas contains malformed polygons with zero size that needs to be pruned first.