refer to CASA recognition of ADF qualifications.
you just need Irex and a flight test . however in order to do a flight test you need an endorsment on type. you will probably need to learn fixed card ADF and the different type of VOR instrument that are common in GA twins.
the test and irex will include CAO's and civil regs.
Remember you are getting the endorsement to fly a light twin in Oz. They are a real handful single engine.
Plenty have gone before you (ADF) and nobody is really interested in why you should not have to do the test.
So best just get on with it and learn what you can.
I would recommend AD Astral in Perth as a very professional outfit.