I am not a programmer, but you could try this.
Add a button to your worksheet and paste the following into the on click event. I am not sire how to show leading zeros in excel but this will put the zero in as text. Hope it helps.
Private Sub CommandButton1_Click()
Dim CellValue
On Error GoTo 1
Set lookfor = Application.InputBox( _
prompt:="Select a cell", Type:=8)
Application.Goto Reference:=lookfor
CellValue = Selection
If CellValue = "" Then
GoTo 1
Else
ActiveCell.Value = "'0" & CellValue
End If
1
End Sub