How about :

       String activeLogFile = "a file name of your choice";
        LoggerContext loggerContext = (LoggerContext) LoggerFactory.getILoggerFactory();
        RollingFileAppender<ILoggingEvent> appender = new RollingFileAppender<ILoggingEvent>();
        appender.setContext(loggerContext);
        appender.setFile(activeLogFile);

        String archiveDir = "a directory of your choice"
        createIfNeeded(archiveDir);
        TimeBasedRollingPolicy<ILoggingEvent> timePolicy = new TimeBasedRollingPolicy<ILoggingEvent>();
        timePolicy.setFileNamePattern(archiveDir + patternFor("%d{yyyy-MM-dd,aux}/%d{yyyy-MM-dd-hh}"));  // hourly
       .....