DD, unless his Perth location is in Scotland, I'd wager he's asking about new CASA exam. Australia. New 'Part 61' mess, oops, system, has given me some headache/extra expenses already, too.
Civil Aviation Safety Authority - Pilot Instructor Rating Common Examination (PIRC)
called PIRC. Pilot instructor rating common. See info above.
Basically, the Heli instructor manual by NZ CAA/CASA and more importantly the principles of instruction/methods of the FAA handbook, also downloadable online from FAA website. Feedback on BS forum and the Oz specific section of pprune (either or both, can't remember) says the FAA book was the main source, but good to know both.
Yet another extra hoop to jump through. The pre-requisite is PPL or higher licence and it's common for both H and A, so you can sit it whenever, even if you plan doing FI course, whole or conversion later in year or so.
CASA FI Aeroplane manual pdf link
CASA FI helicopter manual pdf link
FAA Aviation instructor handbook pdf link - 17MB