Ok, not exactly the answer you are looking for, but anyway: The reason that REST is used in Webservices with high traffic (e.g. Google), is that REST is designed to be cacheable - whereas SOAP is just NOT designed to be cachable.
SOAP is basically based on (per HTTP definition) non-cacheable POST requests, and REST uses GET - which is easy to cache.
You would have to inspect the SOAP (POST) request before it goes to the actual Webservice - i.e. using a proxy. "Standard" proxies are usually unaware of SOAP syntax.
IBM's WebSphere Application Server though can do that:
Regards, Olaf