I assume that in your PayPal Account in Australia you can sign up to use the API's and get a Username, Password and Signature ?
If yes then there should be a PDF download available to you detailing what needs to be done to integrate PayPal Express I suspect that in the code block for PayPal Express inserted at the top of the page when using the wizard you would change the currency from "USD" to "AUD" and the system from WPPro to whatever the integration spec gives you as the value.
Hope that helps.