Generally it involves a 3rd certificate via tafe or university, and a minimum required number of hours work under another qualified electrician,
The fastest way through it would be to complete as much of the tafe stuff via prior learning acknowledgement, to this end you might research the curriculum, as you can access that without being enrolled
The work under another electrician is the harder part depending on your free time, there is no easy legal way around this
AS an alternative fast-path, aim for the disconnect / reconnect license, this can be gained with limited site work, and can be done with prior learning / practical exams / a lot of studying the wiring standards you can get while enrolled for a tafe course through the library.
This will let you run and fit out most of the wiring, but prior to any connection to mains you then have an electrician come and give it there mark of approval and perform the final connection
Most people who are in this position seem to prefer the second option, calling a sparky for a final verification is generally a much shorter and cheaper option than the sparky doing the fit out (so long as it meets all required standards)