I am new to infragistics products.  This forum seems quite weak on examples and answers to questions.  After muddling through many partially answered questions, I worked out a way to skip columns I don't want the grid to stop at.  Here is the code that I pieced together from the sample referenced in one reply.  This code will jump to the 8th (index 7) cell (as my readonly cells are at the left of the grid)  Fro some reason, the readonly property is not exposed in the javascript.  

        function wdg_Activation_ActiveCellChanging(sender, eventArgs) {

            ///<summary>

            ///

            ///</summary>

            ///<param name="sender" type="Infragistics.Web.UI.WebDataGrid"></param>

            ///<param name="eventArgs" type="Infragistics.Web.UI.ActiveCellChangingEventArgs"></param>

            var grid = $find("<%= wdg.ClientID %>");

            var cell = eventArgs.getNewActiveCell();

            var row = cell.get_row();

            var newEditCell = null;

            if (cell.get_index() < 6) {

                newEditCell = row.get_cell(7);

            }

            if (newEditCell != null) {

                var editingBehavior = grid.get_behaviors().get_editingCore().get_behaviors().get_cellEditing();

                // timeout needed to avoid entering exitEdit mode again - and end in recursion / stack overflow

                window.setTimeout(function() {

                    editingBehavior.enterEditMode(newEditCell);

                }, 200);

                return false;

            }

        }