After so many R&D ,...I am able to configure the config to specify log file path and other stuff for Exception and log
below is the sample web.config which says the methods how we can configure
footer="---------------------------------------- Copy Right : DBLayer2008"
formatter="Text Formatter" listenerDataType="Microsoft.Practices.EnterpriseLibrary.Logging.Configuration.FlatFileTraceListenerData, Microsoft.Practices.EnterpriseLibrary.Logging, Version=3.1.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a"
traceOutputOptions="DateTime" type="Microsoft.Practices.EnterpriseLibrary.Logging.TraceListeners.FlatFileTraceListener, Microsoft.Practices.EnterpriseLibrary.Logging, Version=3.1.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a"
name="StarMark Exception FlatFile TraceListener" />
footer="----------------------------------------Copy Right DBLayer"
formatter="Text Formatter" listenerDataType="Microsoft.Practices.EnterpriseLibrary.Logging.Configuration.FlatFileTraceListenerData, Microsoft.Practices.EnterpriseLibrary.Logging, Version=3.1.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a"
traceOutputOptions="DateTime" type="Microsoft.Practices.EnterpriseLibrary.Logging.TraceListeners.FlatFileTraceListener, Microsoft.Practices.EnterpriseLibrary.Logging, Version=3.1.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a"
name="Starmark FlatFile TraceListener" />
traceOutputOptions="None" type="Microsoft.Practices.EnterpriseLibrary.Logging.TraceListeners.FormattedEventLogTraceListener, Microsoft.Practices.EnterpriseLibrary.Logging, Version=3.1.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a"
name="Formatted EventLog TraceListener" />
traceOutputOptions="None" type="Microsoft.Practices.EnterpriseLibrary.Logging.TraceListeners.XmlTraceListener, Microsoft.Practices.EnterpriseLibrary.Logging, Version=3.1.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a"
name="Starmark XML Trace Listener" />
name="Text Formatter" />
formatterType="Microsoft.Practices.EnterpriseLibrary.ExceptionHandling.TextExceptionFormatter, Microsoft.Practices.EnterpriseLibrary.ExceptionHandling, Version=3.1.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a"
priority="0" type="Microsoft.Practices.EnterpriseLibrary.ExceptionHandling.Logging.LoggingExceptionHandler, Microsoft.Practices.EnterpriseLibrary.ExceptionHandling.Logging, Version=3.1.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a"
name="Starmark Exception Log Handler" />
Check this links
http://www.codeproject.com/KB/architecture/GetLoggingWithEntLib.aspx
http://www.codeproject.com/KB/aspnet/ExceptionHandling.aspx
for more details.........