public static void SetSnapMode( 
   LayoutSnapMode mode,
   bool value
)

{
  // sets only the Guide snapping mode 
  ArcGIS.Desktop.Layouts.LayoutSnapping.SetSnapModes(new[] { LayoutSnapMode.Guide });
  // sets only Element and Page snapping modes
  ArcGIS.Desktop.Layouts.LayoutSnapping.SetSnapModes(new[] { LayoutSnapMode.Element, LayoutSnapMode.Page });

  // clear all snap modes
  ArcGIS.Desktop.Layouts.LayoutSnapping.SetSnapModes(null);

  // set snap modes one at a time
  ArcGIS.Desktop.Layouts.LayoutSnapping.SetSnapMode(LayoutSnapMode.Margins, true);
  ArcGIS.Desktop.Layouts.LayoutSnapping.SetSnapMode(LayoutSnapMode.Guide, true);
  /// LayoutSnapping.SetSnapModes(new[]{ LayoutSnapMode.Guide }); // sets only the Guide snapping mode 

  // get current snap modes
  var snapModes = ArcGIS.Desktop.Layouts.LayoutSnapping.SnapModes;

  // get state of a specific snap mode
  bool isOn = ArcGIS.Desktop.Layouts.LayoutSnapping.GetSnapMode(LayoutSnapMode.Guide);
}