code:
function listentoswitch()
{
  enabled = new ActiveXObject("WScript.Shell").RegRead("HKCU\\Software\\Microsoft\\MSNMessenger\\PerPassportSettings\\" + Messenger.MyUserId + "\\ShowTransientPSM");
  if (enabled == 1) { var value = 0; } else { var value = 1; }
  new ActiveXObject("WScript.Shell").RegWrite("HKCU\\Software\\Microsoft\\MSNMessenger\\PerPassportSettings\\" + Messenger.MyUserId + "\\ShowTransientPSM", value, "REG_DWORD");
  var OldMsg = Messenger.MyPersonalMessage;
  Messenger.MyPersonalMessage = "";
  Messenger.MyPersonalMessage = OldMsg;
}
But Indeed, this disables the feature completely, there's no way to show the psm when the currentmedia is active.