I've been trying to do this on a few sectors (roughly a LHR-PVG-MEL-SYD-HKG-LHR journey) and as far as online bookings go, the answer is emphatically no - as soon as you get away from European or domestic fares, the one way fares seem well in excess of a full cash return fare. If you do have any luck by phone, would be good to hear about.