Unusable with multiple message parts ?

[Captain-P-Goldfish]

I just tried to setup a webservice client to consume an existing service. The WSDL has an operation defined as follows:

...
<message name="RequestCertificate_Req">
		<part name="callbackIndicator" type="ns:CallbackIndicatorType"/>
		<part name="messageID" type="ns:OptionalMessageIDType"/>
		<part name="responseURL" type="ns:OptionalStringType"/>
		<part name="certReq" type="xsd:base64Binary"/>
	</message>
...
<operation name="RequestCertificate">
			<input message="tns:RequestCertificate_Req"/>
			<output message="tns:RequestCertificate_Res"/>
		</operation>
...

I am not able to find a reliable way to consume this endpoint with spring-ws since it allows only to add a single object and the RequestCertificate_Req object is not generated with jaxb maven plugin since the service interface is generated with the specific message parts. So how should I be able to use spring-ws client on such a service?