You can use the SOAPProcessor if the webservice endpoints are running in the same container. I suspect you'll still run into the single port issue however. We hope to sort this out in the 4.7 release with a proper Http Gateway that can handle multiple contexts.
v4.6 is just about to be released and it will contain a SOAPProxy action that should make webservice proxying a lot easier. Again however, it will not solve the single port issue.