Green’s Dictionary of Slang

(Aus.) to pick up experience; thus jackarooing n.

1889		B. Mitford Fire Trumpet I 192: I am jackaroo-ing there, as they say in Australia.
1890		‘Rolf Boldrewood’ Colonial Reformer I 147: Perhaps the young one’s going jackerooing at Jedwood.
1898		Eve. Post (Wellington) 9 Apr. 1: I was jackerooing on Mangoburra.
1910		C.E.W. Bean On the Wool Track 41: When the boss is young, working on his father’s station, or jackerooing.
1936		A. Russell Gone Nomad 12: My graduation in jackerooing, or, as I usually call this period of my life, my ‘pack-mule and damper days’ had begun.
1951		Cusack & James Come in Spinner (1960) 375: If you’d like to come and give us a hand over Christmas. Not just jackerooing, but a real job.
1962		F.M. Cutlack Breaker Morant 30: They were jackerooing together on Nelungaloo station in the eighties.