signing a soapenvelope from a client using RPC, help

[Paul Tomsic]

I'm passing a bean thru soap using the
serializer/de-serializer.  How do I sign the envelope
prior to sending it out?
The bean that I'm sending out is simply a wrapper for
a org.w3c.dom.Document w/ a getter/setter method(s).
(code below)
Simply using the example SignedSOAPEnvelope.java that
comes w/ AXIS, the constructor for call.invoke is that
signed soap envelope, but how do i do this w/ my
serialized bean?
Here's the relevant code that works w/o signing but
where would I create the signed envelope?

MyBean mybean = new MyBean();
mybean.setDoc(this.xml_document);

Call call = (Call)service.createCall();
QName qn = new QName("urn:SoapService", "Map");
call.registerTypeMapping(MyBean.class, qn, 
                    new BeanSerializerFactory(MyBean.class,
qn),
                    new BeanDeserializerFactory(MyBean.class,
qn));
call.setTargetEndpointAddress(new
java.net.URL(this.endPoint));

call.setOperationName(new QName(SERVICE_NAME,
REMOTE_METHOD_NAME));

call.addParameter("arg1", qn, ParameterMode.IN);

call.setReturnType(XMLType.XSD_STRING);
this.strResult = (String)call.invoke(new Object[]
{mybean});

thanks