procedure TForm1.Button3Click(Sender: TObject);
var
  ex: Variant;
  wb: Variant;
begin
  ex := CreateOleObject('Excel.Application');
  wb := ex.WorkBooks.Add;
  ex.Visible := true;
  wb.WorkSheets[1].Cells[1,1] := '123.321';
  wb.WorkSheets[1].Cells[1,1].NumberFormatLocal := '_-$* #,##0_-;-$* #,##0_-;_-$* "-"_-;_-@_-';
  {
    ActiveCell.FormulaR1C1 = "123.321"
    Range("D11").Select
    Selection.NumberFormatLocal = "_-$* #,##0_-;-$* #,##0_-;_-$* ""-""_-;_-@_-"
  }
end;