Many of the Chelonia (Turtles and tortoises) are listed on CITES, and as Australia is a signatory to CITES, you would also need CITES IMport Permits from DEH in Canberra as well as CITES Export permits from the country you are acquiring them from. You'd need a pretty good reason too. (Taronga Zoo wanted to bring in some elephants for conservation purposes, and they almost failed because they couldn't get the permits).
Then there is quarantine Import Permits, and you can't get one of them until Biosecurity Australia has conducted an Import Risk Analysis. Assuming you were successful the Quarantine Permit would state that the animals would undergo up to 13 months quarantine on arrival (which you would pay through the nose for), and after that it would be released to you where it would stay under permanent quarantine surveilance and would never be bred.
If you succeed, then there'd be state permits from the DEC too. And they would be ongoing (renewed every year or two).
Would probably be easier and cheaper find something native that does do it for you.
Hix