Your main source of information will be the website of the Embassy of Ireland(external link) in Wellington.
For further details please contact:
Embassy of Ireland
Level 10, Technology One House
PO Box 11498
86 Victoria Street
Consular hours by phone 8.30-12.30. In person by appointment only.
Phone: 00 64 4 471 2252
Website: New Zealand - Department of Foreign Affairs (dfa.ie)(external link)
Web page for Working holidays: Working Holiday Authorisation - Department of Foreign Affairs (dfa.ie)(external link)
The Irish Immigration Department(external link) also provides information on visas for Ireland.