Cursor Position In Viewport

Is it possible to get the position, either relative to the viewport, or the application window, of a specified Point3D inside the viewport? In other words, with the camera at a particular position/orientation, does the toolkit provide a method for determining what the cursor position would need to be in order to point at a specified position in the 3D view? Essentially I'm trying to do the opposite of hit testing, get mouse position out of a 3D position in the view.