You can use the JBossWS stack as a WSSE-enabled client as well. The concept is similar to the server-side case.
Developer.com has a good article on this topic, entitled Securing Web Services in JBoss Application Server with WS-Security.
The chapter Securing the client using WS-Security (page 3) contains specific information about how you can configure WSSE on the client side.
I hope it helps.