I'm not sure how (or if) you can do this on the BindingList.

In the grid you can sort by setting the SortIndicator property on a column. I would recommend that you do this in the InitializeLayout event of the grid.

This will display a SortIndicator on the column header and unfortunately, there's no property to disable sorting by the user and still sort the data programmatically.

But what you can do is handle the BeforeSortChange event and cancel it. So the code would look like this:

        private void ultraGrid1_InitializeLayout(object sender, Infragistics.Win.UltraWinGrid.InitializeLayoutEventArgs e)
        {        
            e.Layout.Bands[1].Columns["column key"].SortIndicator = SortIndicator.Ascending;           
        }

        private void ultraGrid1_BeforeSortChange(object sender, BeforeSortChangeEventArgs e)
        {
            e.Cancel = true;
        }

If you like, you can Submit a feature request to Infragistics and perhaps the ability to sort and disable user sorting can be adding in a future release.