Hi Jootie,

A long custom list can be added programmatically.

Try:

'======================>>
Public Sub Tester001()

   Dim rng As Range
   Dim WB As Workbook
   Dim SH As Worksheet

   Set WB = ActiveWorkbook            '<<========== CHANGE
   Set SH = WB.Sheets("Sheet1")       '<<========== CHANGE
   Set rng = SH.Range("A1:A2000")    '<<========== CHANGE

   Application.AddCustomList ListArray:=rng

End Sub
'<<======================

Change the workbook and worksheet names to suit and change the address of
rng to accord with your list.

If you are not familiar with macros, you may wish to visit David McRitchie's
'Getting Started With Macros And User Defined Functions' at:

http://www.mvps.org/dmcritchie/excel/getstarted.htm

---
Regards,
Norman

The custom list limit is about 254 items, or 1818 characters, whichever
it hits first. AFAIK, there's no way to change the limit, manually or
programmatically.