PrintDialog - assign default values

I have a label printer. Seiko SLP-440. When I ShowDialog the PrintDialog to print a visual the user has to click printing preferences, advanced, paper size to set the paper size. There are a lot of different label sizes.  How can I assign both the default printer and the paper size before ShowDialog the PrintDialog? 

thanks,

  public static void PrintLabel(
   this BitmapSource InBms, Thickness InMargin,
   string InDescription = "Bitmap image")
  {
   PrintDialog pd = new PrintDialog();

   bool? ret = pd.ShowDialog();
   if (ret.Value == true)
   {
    Grid drawingArea = new Grid();
    drawingArea.Width = pd.PrintableAreaWidth;
    drawingArea.Height = pd.PrintableAreaHeight;

    Image im3 = new Image();
    im3.Margin = InMargin;
    im3.Source = InBms;
    im3.Stretch = Stretch.Fill;
    drawingArea.Children.Add(im3);

    Rect rect = new Rect(0, 0, pd.PrintableAreaWidth, pd.PrintableAreaHeight);
    Size size = new Size(pd.PrintableAreaWidth, pd.PrintableAreaHeight);
    drawingArea.Arrange(rect);
    drawingArea.UpdateLayout();

    pd.PrintVisual(drawingArea, InDescription);
   }
  }