How to set STDERR logging file to stderr_yyyymmdd.log  instead of stdout_yyyymmdd.log in Tomcat 6.0

I've setup a TOMCAT 6.0 + Apache 2.2 in Windows 2003, connecting them using mod_jk.so and everything works fine.  When I write a jsp file and try to print out some log using System.out.println and System.err.println, they all go into the same log file "stdout_20080417.log".  I wonder there is some property file or some JVM setting which redirect the STDERR to STDOUT.   I have not change any configuration in $TOMCAT_HOME/conf/logging.properties and also unable to find the location to set the STDERR / STDOUT.  Please help.