SendMessage(FindWindow(null, "Map - Microsoft MapPoint North America"), WM_COMMAND, 35388, 0);
after some Spy++ investigational work, i found that this is what needs to be sent in mappoint 2009:
SendMessage(FindWindow(null, "Map - Microsoft MapPoint North America"), WM_COMMAND, 35221, 0);
So there you have it. I hope this helps.