Private Declare Function SetWindowLong Lib "user32" Alias _
  "SetWindowLongA" (ByVal hwnd As Long, _
   ByVal nIndex As Long, ByVal dwNewLong As Long) As Long
 
Private Declare Function GetWindowLong Lib "user32" Alias _
  "GetWindowLongA" (ByVal hwnd As Long, _
   ByVal nIndex As Long) As Long
 
Private Const GWL_STYLE = (-16)
Private Const ES_NUMBER = &H2000&
 
Private Sub Form_Load()
    Dim o As Object
    Dim oldStyle As Long
 
    For Each o In Form1.Controls
       If TypeOf o Is TextBox Then
           oldStyle = GetWindowLong(o.hwnd, GWL_STYLE)
           SetWindowLong o.hwnd, GWL_STYLE, oldStyle Or ES_NUMBER
           o.MaxLength = 2
       End If
    Next
End Sub