Public Function RgxDate(astring As Range) As String
    Dim tempString
    Dim RegExp As Object
    Set RegExp = CreateObject("vbscript.regexp")
    With RegExp
        .Global = True
        .IgnoreCase = True
        .Pattern = "(\d{2}).(\d{2}).(\d{4})"
        RgxDate = .Replace(astring, "$1-$2-$3")
    End With
End Function
 
Public Sub CheckDate()
    Dim MyRange As Range
    Dim C As Range
    On Error Resume Next
    Set MyRange = Application.InputBox(Prompt:="Âûáåðèòå äèàïàçîí", Type:=8)
    If MyRange Is Nothing Then
        MsgBox "Äèàïàçîí íå âûáðàí"
    End If
    For Each C In MyRange
        C.Value = RgxDate(C)
    Next C
End Sub

Public Function RgxDate(astring As Range) As String
 Dim re As RegExp
 Dim tempString
 Set re = New RegExp
 re.Global = True
 re.IgnoreCase = True
 re.Pattern = "(\d{2}).(\d{2}).(\d{4})"
 RgxDate = re.Replace(astring, "$1-$2-$3")
End Function

Public Sub CheckDate()
Dim MyRange As Range
On Error Resume Next
Set MyRange = Application.InputBox(Prompt:="Выберите диапазон", Type:=8)
    If MyRange Is Nothing Then
        MsgBox "Диапазон не выбран"
    End If
For Each C In MyRange
      C.Value = RgxDate(C.Value)
Next C
End Sub