There is no such thing as transferring to the Australian forces.
You have to leave whatever force you are in before you can go over to Oz.
I have been in contact with the relevant department in Australia and they recommend you start the application process at least 12 to 18 months before you are due to leave.
They tend to recruit from SNCO and above with the possiblity of you going down by one rank when you arrive (although not always) In exceptional circumstances they may recruit from those below SNCO depending on trade etc.
Have a look on the Australian Defence Force website for all the necessary information.
However for those who are interested then this address might help out.
PO Box 225
The Australian Army Overseas Transfers are only open to people that are currently serving or have previous military service with a foreign defence force and meet the skills required by the Australian Army.