I'm not aware of anyone adding the factory cruise option to the Micra.
I have seen people do this to other cars, though. In some (lucky) cases, all that's required is the factory switch -- and the wiring harness connector is sitting there waiting for it.
In other cases (eg. Mitsubishi Mirage), the car may need additional hardware like a clutch switch (which cancels cruise if the pedal is depressed). That car also requires a setting changed in the car's computer, which can only be done with a special cable & software.
I'd recommend having a look through the U.S.-based Nissan Versa forum. It's more likely to have an answer, and the car is based on exactly the same platform and drivetrain as our Micra (though not the same drivetrain as your Aussie Micra).
View my fuel log 2015 Micra S manual: 5.0 L/100 km ... 56.5 mpg (Imp) ... 20.0 km/L ... 47.0 mpg (US) ...