Trans Tasman Agreement.
Go to the NZ CAA website and find the aircrew licencing section...it's simply a matter of download form, fill out, attach required supporting documentation and forwarding with fee to NZ CAA in Lower Hutt...takes maybe a few weeks to recieve by return mail. You must have a current Oz medical of course and if you want an ATPL you must have a current Instrument Rating...not sure for CPL.