I don't know how this would be done actually. I would most definitely have to build a custom importer exporter. In my experience both post and term id's can be changed during an import/export using the plugin.
The Taxonomy Images plugin stores only the
attachment_id for each association. I designed it this way to maximize the number of associations that can be stored for an installation. If these numbers change during import/export then the values in the plugin's option would be useless.
When moving data to a new installation. I always use mysql import/export as you get all of the data and not just what passes the importer's filters.
Open to hearing suggestions here. And if I am wrong about anything please let me know. I have only minimal experience using the importer.