Private Sub cmd_Convert_Click()
    Dim XLAPP As Object
    Dim CurrentPrint As Integer
    Set XLAPP = CreateObject("Excel.Application")
 
  XLAPP.Visible = True
  XLAPP.workbooks.Open ("C:\tonline_11032004_1339.dat")
  XLAPP.activeworkbook.sheets(1).Columns(1).Insert shift:=xltoright
  XLAPP.cells(1, 1).Formula = "KEY"
  XLAPP.cells.Select  
 
Ersetzen   '  hier wird deine Sub aufgerufen
 
 
Sub Ersetzen()
    Dim strOld As String
    Dim strNew As String
    strOld = "Hallo"
    strNew = "Test"
    Selection.Replace What:=strOld, Replacement:=strNew, LookAt:=xlPart, _
    SearchOrder:=xlByRows, MatchCase:=False, SearchFormat:=False, _
    ReplaceFormat:=False
End Sub