Server-Side:
    public ActionResult AddAClickEvent()
        {
            Map map = new Map("Map1", new System.Web.UI.WebControls.Unit(100, System.Web.UI.WebControls.UnitType.Percentage), 510);
            map.MapBackground.BackgroundBrush = new GeoSolidBrush(GeoColor.FromHtml("#E5E3DF"));
            map.CurrentExtent = new RectangleShape(-125, 72, 50, -46);
            map.MapUnit = GeographyUnit.DecimalDegree;

            WorldMapKitWmsWebOverlay worldMapKitOverlay = new WorldMapKitWmsWebOverlay("WorldMapKitOverlay");
            map.CustomOverlays.Add(worldMapKitOverlay);
            
            LayerOverlay layeroverlay = new LayerOverlay("MarkerOverlay"); 
            layeroverlay.IsBaseOverlay = false;
            map.CustomOverlays.Add(layeroverlay);
            return View(map);
        }

        [MapActionFilter]
        public string ClickEvent(Map map, GeoCollection<object> args)
        {
            InMemoryFeatureLayer inmLayer = new InMemoryFeatureLayer();
            inmLayer.InternalFeatures.Add(new Feature(0, 0));
            inmLayer.ZoomLevelSet.ZoomLevel01.ApplyUntilZoomLevel = ApplyUntilZoomLevel.Level20;
            inmLayer.ZoomLevelSet.ZoomLevel01.DefaultPointStyle = PointStyles.Capital1;

            LayerOverlay co = (LayerOverlay)map.CustomOverlays[1];
            co.Layers.Add(inmLayer);
            return co.Id;
        }


Client-Side:

<script language="javascript" type="text/javascript">
    function mapClick(e) {
        var params = { x: e.worldXY.lon, y: e.worldXY.lat };

        Map1.ajaxCallAction('@ViewContext.RouteData.Values["Controller"].ToString()', 'ClickEvent', params, mapCallback);
    }

    function mapCallback(result) {
        if (result.get_statusCode() != '404') {
            var a = result.get_responseData();
            var layer = Map1.getLayer(a);
                       layer.redraw(true);
//            Map1.redrawLayer(a);
        }
    }
</script>