It's all possible

To ride on a NZ road you need

1. A valid drivers license, and international driving permit.

2. Registration - this is basically a gov't enforced insurance policy for MEDICAL help. The insurer is a gov't agency called Accident Compensation Corporation or ACC. They do not cover damage to any goods, vehicles or any property. It costs about $230 NZ per year. If you don't have it you will be fined about $200. If you're not displaying the sticker and park your bike anywhere and a parking warden sees it he will fine you $200. Get the 'rego' as us kiwis call it from any post office.

Don't quite know the ins and outs if you don't have NZ plates, but I'm sure it's not that hard. Customs should be able to help. Last I looked the minimum period was 3 months, but you can get a refund on the unused portion.

3. A warrant of fitness. (WoF) This is a technical inspection and costs about $25 - $35. Any bike shop can do it. Basically you need lights, indicators, horn, functioning brakes and non worn wheel/steering head bearings and suspension bushes. Tyre tread needs to be 1.5 mm deep or more around the whole tyre and across 3/4 of the width of the tyre. Don't fuss about it too much, it's usually very easy to get. As long as you're not riding a total wreck you'll pass the inspection.

3rd party insurance is NOT compulsory but highly recommended. If you crash into someone Porche you'll be buggered. Try john baker insurance

You basically have two choices regarding import duty at the border.
1. Get a carnet de passage
2. Pay duty at the border, which you will get refunded when you leave. (the duty rate is 17.5%)

You can find info here.

Tourist Vehicles

Any motorcycle shop will help you sort it out. Apparently Kerry at Motohaus Auckland has helped a few travelers.

Are you going to fly your bike or put it in a container?!

For shipping contact mainfreight. They're the big players in the NZ transport market and know what's what. If they can't help try oceanbridge. They do more 'special projects' cargo

If you're flying your bike try Air New Zealand cargo.

Road rules etc can be found here.

Another very important point: Make sure your bike is spotlessly clean. MAF will sting you with a huge fine for fumigation and cleaning if there is any mud or other organic matter on it.

Good luck