Elinchrom makes 2 versions of the 600RX (see page 12 of the manual). One is for 230v (215-240) and the other is for 120v (110-120). As others have said, often such units are identical, with an internal switch or jumper wire that can be used to change the voltage. You should contact Elichrom and ask about this.
On their Website, they ask that you contact their local distributor. In Australia, that would be:
Kayell Australia Pty Limited
108 Johnston Street
3066 Collingwood VIC
Phone: 03 8412 2800
Fax: 03 8412 2899
They have an e-mail address and a Website but APUG won't let me post the links because I have not yet posted enough messages. Check Google for Kayell.
If the units can not be adjusted for 240v, then you will need stepdown transformers. In any case you will need an adaptor for the wall plug.