From qantas.com.au:
Changes to Qantas Club access when flying Emirates
To enjoy access to domestic and international lounges for travel from 1 October 2014, you need to have a QF or JQ flight number on your ticket for your onward flight. As with all our other airline partners, this change means that as a Qantas Club member you need to book a QF flight number to access Qantas and Partner lounges when travelling in Economy on Emirates.
Choose Qantas to enjoy the lounge
Qantas (QF) flight numbers are available on all Emirates flights to and from Australia and New Zealand, the majority of destinations between Dubai, Europe and the Middle East, as well as key destinations in Africa. So, to make the most of your membership and enjoy lounge access before you fly, simply book the QF flight number.
Qantas Club members will continue to be able to access the Qantas Club lounges when their next onward flight on that day is on a Qantas or Jetstar flight number.