Your right I dont see anything for setting the x.y either.
Check out this article:
Programming MapPoint via .NET
http://www.mp2kmag.com/a66--location....mappoint.html Code:
Private Sub OnMouseMove(ByVal Button As Integer, ByVal Shift As Integer, ByVal X As Integer, ByVal Y As Integer) Handles Map.MouseMove
Notice this sub declaration the x and y get passed in by mappoint.