<system.diagnostics>
		<sharedListeners>
			<add type="WcfListener"  name="WcfListener"  />
		</sharedListeners>
	</system.diagnostics>

	<system.serviceModel>
		<diagnostics>
			<messageLogging logEntireMessage="true" logMalformedMessages="true"
			 logMessagesAtServiceLevel="true" logMessagesAtTransportLevel="true" />
		</diagnostics>

Public Class WcfListener
    Inherits Diagnostics.TraceListener

    Public Overrides Sub Write(ByVal message As String)
        'write you custom code here
        System.Diagnostics.Debug.WriteLine(message)
    End Sub

    Public Overrides Sub WriteLine(ByVal message As String)
        'write your custom code here
        System.Diagnostics.Debug.WriteLine(message)
    End Sub
End Class