Hi Caffa,
I brought my Mu across with me when I moved to Aus two and a half years ago. Overall the process was a pain in the ass, but worth it in the end. This was as a personal import, don't know about getting a vehicle in that you don't own.
If you get an importing agent to do all the paperwork it might be easier that doing it on your own as I did.
Basically you have to have owned the vehicle for at least one year and have lived in the country where the vehicle is being imported from during the last year (you might want to check on this last point).
In short form this is how it goes....
Apply for and get permission to import.
Ship vehicle.
Take delivery documents to Customs.
Realise you don't have the document they didn't tell you about.
Get new documents and return to customs.
Repeat as required.
Pay money.
Pay GST on top of money already paid.
Arrange an inspection for quarantine.
Wait for them to turn up.
Take inspection documents back to Customs.
Pay more money.
Pickup vehicle from wharf.
Pay more money.
That's it for the importing side. But wait, there's more....
You then have to register it.
Have the vehicle inspected to get a 'blue slip'. Most mechanics can do this.
Pay money.
Get a temporary registration.
Pay money.
Have the vehicle inspected by RTA to check it is the actual vehicle you are trying to register.
In NSW (don't know about other states) you need to get a child seat restraint point fitted to the back. This is a big bar that goes across the back behind the back seats. It can be easily removed. Dealer imported ones don't need this.
Pay money.
Finally it will be ready for registration, so...
Pay more money.
There you go. In all I think it cost about $5k to do mine including shipping, duties, and registration. I left NZ in a bit of a rush (job opportunity) so didn't have time to sell mine and I would have lost too much money on it. Plus I had a nice relocation allowance that took care of most of the cost :-). The import duties are based on the price that you paid in NZ when you bought the vehicle.
If you need any more info then just ask.
Cheers,
Kendrick.