I suggest that you start with NZ records, which are very good. Did he marry in NZ? If so you need to buy a photocopy of the entry, and also for the births of his children. I found that parents' places of birth are often given in detail (not just IOM).

Do you know roughly when he arrived in NZ?
Wellington Archives have name indexes to passenger arrivals up to the late 1880s, from memory - but check with them or with the NZ Soc. of Genealogists.

Corkill was a very common name in the IOM, so you need to get as much information as you can first. Unless you have his exact date of birth?

Sue