Private Declare Function SetTimer Lib "user32" (ByVal hwnd As Long, ByVal nIDEvent As Long, ByVal uElapse As Long, ByVal lpTimerFunc As Long) As Long
Private Declare Function KillTimer Lib "user32" (ByVal hwnd As Long, ByVal nIDEvent As Long) As Long
 
Private Sub Command1_Click()
SetTimer Me.hwnd, 0, 1, AddressOf Go
End Sub
 
Private Sub Command2_Click()
KillTimer Me.hwnd, 0
End Sub
 

Private Declare Function GetAsyncKeyState Lib "user32" (ByVal vKey As Long) As Integer
Dim Tecla$, TeclaVieja$
 
Sub Go(ByVal hwnd As Long, ByVal nIDEvent As Long, ByVal uElapse As Long, ByVal lpTimerFunc As Long)
Tecla = ObtenerTecla
If Tecla <> TeclaVieja Then
TeclaVieja = Tecla
MsgBox "Tecla " & TeclaVieja & " fue pulsada."
End If
End Sub
 
Private Function ObtenerTecla() As String
If GetAsyncKeyState(76) Then
    ObtenerTecla = Chr$(76)
End If
End Function