I'm thinking of building a custom centre console panel to replace the stereo and airco panel. However, what I'd like to do would force me to move the hazard light switch. What are the legal requirements for the switch? Can I even move it at all?

Interesting question. There are two issues i can see.

Firstly, There are specific requirements regarding the lights and the need for the switch, but there does not appear to be an ADR that specifically covers the actual placement of the switch BUT (there's always a but) there are ADR's that cover the ergonomics of the controls.

Secondly, there are state specific regulations that quite often contradict federal rules. To confirm these you would need to check with the SA RTA.

As far as i'm aware:
1. you must retain the switch
2. you can move the switch, but
3. the switch must be as accessible in the new location as it was in the old.

There are no rules to state you can not move it. It needs to be reachable and visable so it can be seen by someone driving the car who is not familiar with the car. Often people move the switch, have thought of moving my hazzard switch to facilitate the fitting of the blue tooth buttons in my wagon.