Its available for download from HTP Members Club. You need to setup an account and then you can doewnload country-specific ROM updates. For Australia they currently have the C730 WM6 customised for Optus and Vodafone Australia networks. Go to
www.asia.htc.com then select Australia and then Service & Support. Follow your nose to the downloads section. If you don't have a members account then you will need to establish one first.
Right, but unless you have an Aussie specific serial number, no joy. My C730s are HK sourced and I can get THOSE roms... just not the Aussie version. And sadly XDA Developers have nothing for the C730 yet.