All configuration files can be found in the directory $NETSERVE_HOME/etc. There is a sample configuration located at $NETSERVE_HOME/etc/sample which can be used template for a custom configuration.
In the file etc/logging.properties log4j is configured. Have a look at the sample configuration.
For further instructions visit the log4j project site.
The etc/server.xml file is the NetServe main configuration file. There is a sample configuration located at etc/sample which can be used as a template for a custom configuration.