I can't answer the question about JAR compliant schools in NZ. Best see the CAA for that one. (My guess is no).
Converting the NZ CPL to a JAR one? You'll need to rob a bank or something. Best thing would be to get a job in either NZ or Oz to get some time up preferably on turbines. (Much harder than it sounds) A NZ licence is acceptable in Australia.
To convert, you'll need to do all 14 JAR ATPL exams + at least 15 hours for the IR. (and the medical etc)