Jeff had a similar posting here for Lifecycles a few days ago.
You use the same enumCustomize tool to change the wt/project/role.class file. The tool is easy to use - you can add additional roles and disable (make "unselectable") default roles from the pull-downs. Be sure to back up all language versions of the role.rb files before using the tool. After you build the resource bundle (rb) file with the tool, change the Windchill shell directory to the codebase, then run the "ant -f makejar.xml" command to recompile the jar files. You should stop the MethodServer and Tomcat and clear the Tomcat servlet cache by deleting the <tomcat>/work/standalone/localhost/<web.app> directory. Restart Tomcat and the MethodServer.