From a quick review of the SOAP and WSDL specs, it does not appear that there is a standard approach for describing the structure of a header node in the WSDL file for a web service.
Is this a correct interpretation?
What is the best practice for communicating SOAP header information to a trading partner or service user?
IS 4.6 does not support automatic generation of WSDL files containing soap:header message definitions.
A best practice guideline seems to be that if your partner plans to auto-generate a client to consume your web serive, it would be a good idea to manually edit the generated WSDL file to add soap:header definitions into the WSDL. If your partner plans to create a client by hand they can work off of a separate schema that defines the request and response header definitions.
Examples of soap:header definitions can be found in the SOAPBuilder Round B Group C test case as well as the WS-security and WS-reliability specs.