Log4j with glassfish

[Drinkwater, GJ \(Glen\)]

Hi 
I will be soon deploying 3 applications which are identical in the code
other than the configuration and the databases they are connected to.
Currently they use log4j. Previously with tomcat I could log different
applications to different log files, but I cannot seem to find a way to
do this with glassfish. 
I was wondering if anyone has any ideas how I could log the 3 apps so
that I can identify the logs to a particular app with log4j???
Glen