you are very near to the solution.
as you did to change the order of the column based on month using list you can do the same using new list for container order.
i assume if 1,2,3,4 is your order the code will go like below.
List<string> l = new List<string>(new string[] { "1","2","3","4" });
protected void ASPxPivotGrid1_CustomFieldSort(object sender, DevExpress.Web.ASPxPivotGrid.PivotGridCustomFieldSortEventArgs e)
{
if (e.Field.FieldName == "containerorder")
{
string val1 = Convert.ToString(e.Value1);
string val2 = Convert.ToString(e.Value2);
e.Result = l.IndexOf(val1).CompareTo(l.IndexOf(val2));
e.Handled = true;
}
}
</string></string>
hope this will help.