Control Excel dialogs with Python?

Question

Using Python and Pythonwin, how do i get python to answer true or yes to dialogs boxes.

  xl = Dispatch("Excel.Application")
  xl.Visible = 1
  xl.Workbooks.Open("C:\pyVBA.xls", True, True)         
  xl.Run("pyVBA.xls!Macro1")

If pyVBA has macro1 has a yesno dialog box (which is fine if visible = 1, but not if visible is = 0), how do i input yes dialog box.