Portal (Http) Session Listener

We would like to have a session listener that is preferrably installed on the webMethods portal application level so that it could be notified of any user login (new session created) regardless of what portlet application the user will be using. Our goal is to be able to access all session information independent of the current session. We saw a web.xml file inside the portal.war and installed a HttpSession listener in it but it doesn’t seem to have any effect. We also try to install a session hook using the session.xml supplied by the portal under the config folder, but it didn’t work neither.
How can we install such a listener? Is there any plugin API in webMethods portal that allow for achieving the same task as in a normal J2EE web application?

Vien Khe