When you'd like to deploy an endpoint with existing WSDL, you need to tell the JAX-WS runtime the association between the WSDL and your service. This is done by adding a few more attributes/elements to the ws:service element like this:
<ws:service bean="#myService" serviceName="tns:fooService" portName="tns:foo" xmlns:tns="http://my/service/nsURI"> <ws:primaryWsdl> <value>/WEB-INF/wsdl/</value> </ws:primaryWsdl> </ws:service>
The portName attribute works like @WebService(portName=...) (except that it's a real QName), and the primaryWsdl element works like @WebService(wsdlLocation=...) (except that it can take forms other than String.) If the primary WSDL is omitted, the runtime will search for WSDL in /WEB-INF/wsdl/ and find one that matches the specified port and service name.
See a complete example contirbuted by Andreas for more details (although this does things slightly differently.)