[logback-user] multiple apps deployed in Tomcat

I want to deploy multiple applications in Tomcat. Each one will include Logback jars. I need to have the log configuration file external to the war so i can change them on the fly. Is the "best" way to do this to have an init servlet in each application which loads from the filesystem? I can pass a system property on Tomcat startup which points to a "config" directory.