I believe you need to purchase the QuickTime Pro key ($29.99 USD). Once you enter the registration number in System Preferences for QuickTime Player 7, it 'unlocks' several export features, including JPEG2000.
See:
http://support.apple.com/kb/SP521
http://support.apple.com/kb/HT3820
http://support.apple.com/kb/HT2240
http://store.apple.com/us/product/D3380Z/A/quicktime-7-pro-for-mac-os-x?fnode=62
-DH