Estoy usando Microsoft Expression Blend 4
Tengo un navegador ...,

[XAML] ConnectionView "Código vacío detrás"

        <WebBrowser local:AttachedProperties.BrowserSource="{Binding Source}">
            <i:Interaction.Triggers>
                <i:EventTrigger>
                    <i:InvokeCommandAction Command="{Binding LoadedEvent}"/>
                </i:EventTrigger>
                <i:EventTrigger EventName="Navigated">
                    <i:InvokeCommandAction Command="{Binding NavigatedEvent}" CommandParameter="??????"/>
                </i:EventTrigger>
            </i:Interaction.Triggers>
        </WebBrowser>  

[ C# AttachedProperties clase

public static class AttachedProperties
    {
        public static readonly DependencyProperty BrowserSourceProperty = DependencyProperty . RegisterAttached ( "BrowserSource" , typeof ( string ) , typeof ( AttachedProperties ) , new UIPropertyMetadata ( null , BrowserSourcePropertyChanged ) );

        public static string GetBrowserSource ( DependencyObject _DependencyObject )
        {
            return ( string ) _DependencyObject . GetValue ( BrowserSourceProperty );
        }

        public static void SetBrowserSource ( DependencyObject _DependencyObject , string Value )
        {
            _DependencyObject . SetValue ( BrowserSourceProperty , Value );
        }

        public static void BrowserSourcePropertyChanged ( DependencyObject _DependencyObject , DependencyPropertyChangedEventArgs _DependencyPropertyChangedEventArgs )
        {
            WebBrowser _WebBrowser = _DependencyObject as WebBrowser;
            if ( _WebBrowser != null )
            {
                string URL = _DependencyPropertyChangedEventArgs . NewValue as string;
                _WebBrowser . Source = URL != null ? new Uri ( URL ) : null;
            }
        }
    }

[ C# ConnectionViewModel Class

public class ConnectionViewModel : ViewModelBase
    {
            public string Source
            {
                get { return Get<string> ( "Source" ); }
                set { Set ( "Source" , value ); }
            }

            public void Execute_ExitCommand ( )
            {
                Application . Current . Shutdown ( );
            }

            public void Execute_LoadedEvent ( )
            {
                MessageBox . Show ( "___Execute_LoadedEvent___" );
                Source = ...... ;
            }

            public void Execute_NavigatedEvent ( )
            {
                MessageBox . Show ( "___Execute_NavigatedEvent___" );
            }
    }

[ C# ViewModelBase class Aqu

Finalmente
La vinculación con comandos funciona bien y los cuadros de mensaje se muestran

Mi pregunta
Cómo pasar NavigationEventArgs como parámetros de comando cuando se produce un evento navegado?