I wrote a huge article titled Configuring log4j.properties on, funnily enough, how to configure Log4J but sometimes it still isn't as good as great example:
log4j.rootLogger = INFO, X
log4j.logger.A.B.C=ALL, X
# or this for custom logger log4j.logger.A.B.C=A.B.C.MyLogger
#set the appender named X to be a console appender
log4j.appender.X=org.apache.log4j.ConsoleAppender
#set the layout for the appender X
log4j.appender.X.layout=org.apache.log4j.PatternLayout
log4j.appender.X.layout.conversionPattern=%m%n
#log4j.logger.A.B.C.appender= blar...
With the help of Example log4j Configuration File