private void Form1_Load(object sender, EventArgs e)
{
    fpSpread1.ActiveSheet.Columns[0].CellType = new CustomCellType();
    fpSpread1.ActiveSheet.Cells[0, 0].Value = 1;
    fpSpread1.ActiveSheet.Cells[1, 0].Value = 2;
    fpSpread1.ActiveSheet.Cells[2, 0].Value = 3;

    fpSpread1.ActiveSheet.AutoFilterMode = FarPoint.Win.Spread.AutoFilterMode.EnhancedContextMenu;
    fpSpread1.ActiveSheet.Columns[0].AllowAutoFilter = true;
}

public class CustomCellType : FarPoint.Win.Spread.CellType.GeneralCellType
{
    public override string Format(object obj)
    {
        if (obj != null)
        {
            return string.Format("{0} : class {1}", obj, obj);
        }
        return base.Format(obj);
    }
}