Event Handlers:
            http://www.ateam-oracle.com/oim-11g-event-handlers/
            http://idmoim.blogspot.com/2011/07/developing-and-deploying-oim-11g-custom_29.html
            http://idmoim.blogspot.com/2014/04/event-handler-handler-deployment-in-oim.html
                http://idmoim.blogspot.com/2011/07/developing-and-deploying-oim-11g-custom_29.html
                http://docs.oracle.com/cd/E14571_01/doc.1111/e14309/oper.htm

Custom user attribute & Event Handdler implementation: 
http://fusionsecurity.blogspot.com/2011/09/oim-11g-event-handler-example.html