It's possible for example with usage of AccessLogValve or RemoteAddrValve. AccessLogValve should be sufficient for your purpose. See here http://docs.jboss.org/jbossweb/7.0.x/config/valve.html the docs for the valves. It seems that patterns %h and %u of AccessLogValve will be most useful for you.
You could see here https://community.jboss.org/thread/174222 how to configure valve in AS7. In GateIn you will need to use file GATEIN_HOME/gatein/gatein.ear/portal.war/WEB-INF/jboss-web.xml . In case that you have GateIn on Tomcat, you may need to configure it in Tomcat7 server.xml file . See Tomcat docs for more info.
Note that this solution is not GateIn specific, but it's provided by application server (JBoss7 or Tomcat7) and you can use it with any other web application.