I've checked nrt-hkg-jfk-sju-lax-dfw-anc-dfw-lax-lhr-dxb-lhr-cpt-jnb-syd-drw-per-hkg-sin-nrt against Mileage Monkey and it's happy. You just won't be allowed more than 2 stopovers in Asia, as that's your continent of origin.
Any comments from the experts out there?
(BA's franchise Comair flies CPT-JNB & QF do JNB-SYD.)