I'm assuming you have access to the HttpServletRequest object - if so, you can create a session context manually and retrieve the Identity instance from it directly:
Context ctx = new SessionContext( new ServletRequestSessionMap(httpServletRequest) ); Identity identity = (Identity) ctx.get(Identity.class);
Actually, that probably won't be enough to perform full authentication. I recommend that you wrap your Seam-specific code in a ContextualHttpRequest, that way you'll get full access to all Seam contexts (and be able to authenticate).
Thanks Shane! It works now (well, most of it :)). I hope that Seam API docs will reach the same level of quality as the Seam framework itself.