I'm afraid that Luca's instructions are for adding Log4j to a single webapp, but you're apparently attempting to add log4j to the Tomcat server itself. Tomcat's documentation doesn't do a very good job of explaining that each webapp is responsible for its own logging and the server itself also has logging which is independent of the webapps. Or at least, it was never clear to me.
Regardless "It doesn't work" doesn't tell us anything useful. We need details. Any error messages that may come from the catalina.out file or any of the other files in the Tomcat log directory would be a good start. Note that if your logging didn't "take", the Tomcat server often places server-specific error messages in the "localhost" log files.
Do make sure that you use absolute file locations for your logfiles. Although in theory relative file locations would be based on the TOMCAT_HOME directory, sometimes it's better to leave no doubt.
When it comes to destroying a civilization, gas chambers cannot hold a candle to echo chambers.