How much experience do you have on the US CPL?
You may find that the NZCAA will not recognise the US CPL and may only issue you a New Zealand PPL based on the US CPL, and even for that to happen you will need a current US CPL.
You may need to do the CPL exams a CPL flight test to get a New Zealand CPL, plus the relevant exams and flight test for the IR if you want that too.
What is your reason for getting a New Zealand CPL? There is no shortage of local pilots so finding work may not be easy.