The solution is to modify the VB code. I noticed that there is a function called PlotMomentTensor in the code. This function create a polygons, lines and points and draws them to the display. To save the geometries as features, you could have three feature classes (one line, point and polygon) already defined that you feed into the function and instead of drawing the geometries on the map, you could create a feature in each feature class and assign the geometry to the feature.
To save the geometries to the mxd, you could create graphic elements (point, polyline and polygon elements), set their geometry and add the elements to the map's graphic container (see IGraphicsContainer.AddElement).
To keep the elements drawing in the IDisplay, you could implement an event listener on the IActiveView.OnAfterDraw, keep a reference to the geometries you are drawing and add the draw
code in the event listener (I would advise against re-running the code to generate the geometries, in the event listener, just keep a reference to them.) This won't save the feature but they will stay in the map long enough to export a pdf.
