There's no jbws feature at the moment for setting a given annotation reader do be used by jaxb for an endpoint. The only supported customization is the JAXBIntros stuff. However, it should not be that hard to add an annotation similar to the Metro @UsesJAXBContext and a deployment processor that looks for that, properly populate a BindingCustomization object and attach it to the current deployment.
If someone is willing to work on this, please create and self-assign a JIRA, I can provide more detailed suggestions / directions if needed.