VFR:
Auckland down the coast to New Plymouth, then to Wanganui (getting fuel if needed), then down the West Coast of the North Island. Cross Cook Strait from Mana Island (get radar control/monitoring across the strait if you want it), then into Omaka.
If you have a bit more time on your hands, make a little detour via Taupo and the volcanoes, but watch out for the military zones north of Waiouru. Stick to the desert road if on the eastern side.
IFR:
WB AAWB 3 H384 TR H472
WB AAWB 4 H277 OR H412 TR H472 (10,000ft and below)