I have a few ICAO licences and the issuing country will generally give credit for your licence, log book hours and type ratings. To issue the licence the new country requires a medical examination, an air law exam and a flight test. I doubt it will be quite that simple in EASA land for a 'third country' licence.
I anticipate that the requirements will be similar to a 10,000 hour Australian CASA ATPL(H) CIR holder applying for a UK licence - all 14 ground examinations, a medical, a flight test, type rating examination and a sizeable bank loan.