Recent changes to the Norfolk Island Immigration Act became effective on 24 May 2013. Those changes allowed Australian & New Zealand citizens greater flexibility to stay on the island longer without making application.
The following links may be useful for you. The most important link is the Norfolk Island Immigration & Norfolk Island Customs direct webpage which contains all the current changes and other useful information.
Norfolk Island Immigration Website
Norfolk Island Immigration Act - Downloadable Document.
Immigration Policy and Guidelines PDF
Norfolk Island Customs Website