If the Active Picture was created using the "embedded data" option, there is no possbility to use a processing cursor. If the "linked data" option was chosen, then you can indeed add / remove processing cursors, change the parameters (i.e. order cut vs. %, freq., order, width, etc.).
Note that the other requirement is that there is already a 2D display window that is part of the Active Picture layout, as there needs to be a place the put the resulting curve; you can't add this after the plot is already in PowerPoint.
As you mention receiving the PPT file from someone else, your only option would be to have them recreate it with a layout that includes both a 3D and 2D plot window, using the "linked data" option. Of course that will also require that you have access to the same network and PC where the data resides, which may or may not be the case.
I've also added a picture with a graphic example of the type of layout required -