It's likely to be contest winners and invitees only.
The 2009 premiere in Sydney was 900 double passes to celeb invitees and 200 single tickets sold online to the public. The Sydney premiere of STiD last Tuesday was two cinemas full of contest winners, plus a few selected invitees (ie. double the size of the event the same organizers trialled a few months ago for the "Hansel & Gretel: Witch Hunters" gala premiere). No ticket sales at all.
Advice from Paramount: Enter every contest you can.
Most of them will be online ones: mobile phones, Facebook, Twitter, etc.