After jbossws webservice deployment , each endpoint will be registered in EndpointRegistry .
You can use jbossws SPI api to retrieve the EndpointRegistry , then get the endpoint you want to change and set your own BindingCustomization. After this setup , the soap request come in and the new BindingCustomization will be used to process the jaxb classes. This is just my draft thought about this problem, not really sure if this can work for your case.