A very “rough” method would be to use a vtkPointPicker, since the input to the glyph mapper is a set of points. You could play with the SetTolerance(tol) of the picker to control how close the mouse has to be to the glyph point. You can also use PickFromListOn() and AddPickList(actor) to restrict picking to certain actor(s).
Honestly, I don’t know how well vtkPointPicker will work in this situation, so take this suggestion with a grain of salt.