I am running JForum on Tomcat with the security manager. It took a while for me to get the security policy created. I basically ran with security debugging on and granted permissions when I saw access errors. I did this until it ran without errors. I have been running a couple of days without access errors so this is pretty close to everything you need. The security is relatively fine grained but in general I gave permissions to all classes and libraries within the application directory to work within the application directory at the access level they needed. I could have given the permissions to specific classes but this would have taken even longer and been more complicated to manage. I think this provides a reasonable security policy. Let me know if you have any suggestions for improvement. I am posting here as a starting point for others.