<Window>
  <i:Interaction.Triggers>
    <i:EventTrigger EventName="Loaded">
      <command:EventToCommand
        Command="{Binding RunListenerCommand}" />
    </i:EventTrigger>
  </i:Interaction.Triggers>
 ....
</Window>

if(!DesignerProperties.GetIsInDesignMode(this))
{
    // запускаем листенер
}