If your data is in matrix form, you can make matrix window active and select the menu item Plot->Contour->Profiles. In the graph that comes up, there is radio control for arbitrary line which can be moved/resized to obtain the x/y projections.
Note that this only works on matrix data. So if your raw data is in XYZ form, perform gridding to create a matrix (rather than directly plotting the XYZ and a triangulated contour)