Placing input header doc inside soap header while creating webservice provider for a flow service

I have created a flow service with inputs as a xml string and a header doc. When I create webservice provider for this service then both header doc and xml strings are reflecting inside SOAP body request. I want xml string inside SOAP body and header doc inside SOAP header. How it can be done?

It does not work that way, use handlers/WS policy files. Refer Webservices Developer Guide.