How pass value objects into EJB methods using EJB adaptor

We have a Webmethods 6.0.1 integration platform coupled with Weblogic 6.1 J2EE platform where our core business logic lies.
B2B orders flow in via Webmethods Proxy server (reverse invoke) into a Webmethods Integration (internal) server with Trading Networks installed.
Our core business logic is accessible via a stateless session bean layer.
Currently, we are using EJB Adapter 1.2 to invoke stateless session EJBs deployed on Weblogic server 6.1. We are able to send only primitive data types from Webmethods flow services to stateless session EJBs. In the stateless session EJBs, we are forced to convert XML strings to Java value objects using JAXB before delegating to the business layer. It will be great if we could create Value objects in Webmethods (using Developer), map appropriate fields using WM Developer and invoke EJBs. All of Webmethods’ EJB adapter documentation/examples show usage of primitive objects as EJB parameters.
Can you point us in the right direction, by example or documentation?