I suppose to implement a custom JUL-LogManager that switches off the JUL configuration completely:

public class Slf4jLogManager extends LogManager
{
public Slf4jLogManager()
{
}

@Override
public void readConfiguration() throws IOException, SecurityException
{
}

@Override
public void readConfiguration(InputStream ins) throws IOException,
SecurityException
{
}

@Override
public synchronized boolean addLogger(Logger logger)

{ return super.addLogger(new Slf4jLogger(logger.getName(), logger .getResourceBundleName())); }

}

public class Slf4jLoggerAdapter
{
private final String name;
private volatile Logger logger;

public Slf4jLoggerAdapter(String name)

{ this.name = name; }

private Logger resolve()
{
Logger logger = this.logger;
if (logger == null)

{ logger = demandLogger(); this.logger = logger; }

return logger;
}

private Logger demandLogger()

{ return LoggerFactory.getLogger(name); }

public Level getLevel()
{
org.slf4j.Logger logger = resolve();
Level level;
if (logger.isTraceEnabled())

{ level = Level.FINEST; }

else if (logger.isDebugEnabled())

{ level = Level.FINER; }

else if (logger.isInfoEnabled())

{ level = Level.INFO; }

else if (logger.isWarnEnabled())

{ level = Level.WARNING; }

else if (logger.isErrorEnabled())

{ level = Level.SEVERE; }

else

{ level = Level.OFF; }

return level;
}

public boolean isLoggable(Level level)

{ return getLevel().intValue() <= level.intValue(); }

public boolean isSevereEnabled()

{ return resolve().isErrorEnabled(); }

// ...
}

public class Slf4jLogger extends Logger
{
private static final Handler BRIDGE_HANDLER = new SLF4JBridgeHandler();

private final Slf4jLoggerAdapter adapter;

public Slf4jLogger(String name, String resourceBundleName)

{ super(name, resourceBundleName); adapter = new Slf4jLoggerAdapter(name); super.setLevel(Level.ALL); super.addHandler(BRIDGE_HANDLER); super.setUseParentHandlers(false); }

@Override
public Level getLevel()

{ return adapter.getLevel(); }

@Override
public boolean isLoggable(Level level)

{ return adapter.isLoggable(level); }

@Override
public void severe(String msg)
{
if (adapter.isSevereEnabled())

{ super.severe(msg); }

}

// ...
}