There are several ways (I’m assuming you have done only pcb or both pcb and breadboard?) You can load a generic 40 pin IC in to the parts editor then select pcb view then File->Load Image for view and feed it your new svg. Then File->save as new part and the fzpz will appear in the mine parts bin. How I would do this is to edit the fzp file directly to add the new svg, the details of this can be found in this tutorial series:
this requires that you understand the underlying file formats for the svgs and the fzp file, if you don’t the parts editor may be easier (but much more limited!)
Peter