'If you leave your non-status Air NZ number in the booking, then NZ wont allow lounge access, even if you wave your KF Gold card. I believe this is not aligned to star alliance current policy, but others hold different opinions.[/QUOTE]

From ThaiKiwi's quote above, I believe that you can change your frequent flyer number to SQ at the door of the lounge, and then your gold status should let you in. I have obtained access to lounges on flights paid for by Airpoints by using a (non-AirNZ) gold star alliance card. Air NZ do not want people accruing to Airpoints and at the same time using non-Airpoints cards to access lounges.

I agree with ThaiKiwi's second sentence that Air NZ's approach contravenes Star Alliance policy. By introducing this uncertainty, it discourages me from flying Air NZ-you want consistency and no surprises when you are travelling and the contradiction between Air NZ's policy and what Star Alliance have stated leads to inconsistency and potential disappointment.