I had success by packing lots of 20 films into black bags then putting inside a vacuum sealer. Works very well... You can get these vacuum sealers quite cheap from homewares type places.

I spent a month in NZ last year for work and i would certainly insist on visual inspection. They use older style X-ray machines at Auckland and Christchurch airports and have potentially much higher radiation levels.

If you are going through customs i'd say leave in canisters in zip lock bags. They are quite inquisitive.