Hi Chris,
Yes, I have the plugin working on a site in production in Australia. Happy to share the code. Recently, Fastway split the AU and NZ API to different sites, so the NZ version would need tweaking to correctly point the API. The code sets the url as a global variable at the top of the code, so it should be a straight forward change.
class plgHikashopshippingAufastway extends hikashopShippingPlugin {
var $baseURL = "
au.api.fastway.org/v3/psc/
";
I have attached the plugin for your use.
Craig