well, from my previous experience using Asiamiles, I can standby on other CX flights (just cuz it's allowed) but when waitlisting for OTHER airlines, i cant cuz the change of ticket needs the other airline to reconfirm then get back.
When I was on paid ticket flying LHR-HKG, i had to follow the ticket rules adn pay change fee.

*When I was last in KIX, I wasn't allowed to standby on another CX flight of the same day*
So there you go...