delete all 3 eventbufferX.ser files in the $WS_HOME\AppServer\profiles\<your Profile name>\wstemp\events do not delete folder 'events' - it won't be recreated.
WAS supports jsf 1.1 at run-time. But may be it would be possible to load jsf 1.2 jars using LOAD_PARENT_LAST classloader policy on WAR level. Will check it later (abdul).
"Specifically, this Early Program provides application developers with a powerful way of constructing Asynchronous JavaScripted XML (AJAX) applications."