Are you looking for a SOAP client for RPC style calls or document format.
For the former adding a simple SOAP Envelope to the request and using ZnClient should work fairly well.
But if you are looking for something like :
http://www.soapclient.com/soaptest.html�� to be used against a declared WSDL.. I doubt if any exists.
Look at the XMLRPC package and see if you can work from there.. if you need to adapt something..