What do you imply as "hotspots that link a part number from a parts list"? Parts list is usually stored as text/table and hotspot is an area on an image.
I would like to see an example pdf that allows the user to click a part number in a parts list and be linked to the parts illustration with the part and callout identified (highlighted).
This would at least require publishing engine to support embedding multimedia objects to PDF. It's not supported yet, but "is on the plan".
As far as I'm aware, currently for PDF output you can only create links (from the parts list in your case) to the appropriate image, without highlighting.