There are no homes in EJB 3.0 and the XML for ejb-refs has not yet been decided by the EG.
Just do a straight JNDI lookup:
ContentServiceSLEjbLocal local = (ContentServiceSLEjbLocal)ctx.lookup(ContentServiceSLEjbLocal.class.getName());
It turned out that my actual problem was that I had 'build before lauch' set in Eclipse and it was compiling my classes rather than my ant script. Now I've turned the option off and removed the ejb-refs from my web.xml everything works fine.