What type of java client will be using the WCF service
You probably will have your best luck with the BasicHttpBinding; of course this certainly could change based on your requirements.
Dave
You will need to use a java toolkit that supports WS-I BP.
Also, here are a couple resources for enabling java/WCF interop in more advanced scenarios.
http://java.sun.com/webservices/interop/reference/tutorial/doc/index.html
http://java.sun.com/developer/technicalArticles/glassfish/ProjectTango/