Originally Posted by
zoovet
Sorry that is probably something you can't do, as there is no international lounge access in Auckland for arriving passengers. You will have to stick to your original plan and shower at the domestic lounge.
There are showers available for arriving international passengers once they are landside. From Auckland International Airport website (link cited above):
Showers facilities are available for passengers free of charge just outside the international arrivals gate. Towels and bathroom essentials are available to buy from Relay and iSite Tourism Information Centre. Both sites are situated on the ground floor arrivals in the international terminal.