You have a few choices:
1. use QF Frequent FLier points (miles) to upgrade pending availability of award seats in J.
2. use QF Frequent Flier upgrade credits pending availability of award seats in J.
3. QF issue complementary upgrades for operational purposes, generally to premium FF members.
4. Part with your cash and purchase a J ticket. This is the only way to ensure you get to fly business class.