Actually it isn't as bad as some are saying.
You need to talk to ASL, not the CAA, as ASL carry out foreign licence validations. All the info you need can be found here:
http://www.caa.govt.nz/pilots/Flight...ition_Info.pdf
In general, for an ATPL, if you have an ICAO ATPL licence that is valid in ALL respects, you can expect to have to do a NZ ATPL law exam and an ATPL flight test (and get a NZ Class 1 medical). If you get a job with an airline here, the flight test can be incorporated into a proficiency check. If you do the flight test independently, you will need a small turboprop (possibly a Mojave if it is still around).
I just did it, turned out to be pretty straightforward.
PM me if you want.