I wouldn’t even bother with the ASEL ATP. The regionals will take you with a multi engine commercial or ATP (AMEL, airplane multi engine land). It would probably cost you less to do the commercial since you would not have to spend money on the ATP-CTP course. The regionals all have their own courses for that and they include it in their training.
Some airlines have hired Australians and have been able to hire them without any FAA certificates and they get issued the ATP when they finish their training. The airlines that hired Australians have been SkyWest, Mesa, Piedmont, Expressjet, Commutair, Gojet, and TSA.