Need Flexinode field type similar to the Categories fields

Can you create a flexinode field type that will list certain flexinode (or other) content type pages as a category listing, that would be selectable in the new "Add Content Type" page? Example:

1. For a typical University course you have the Papers that are available and the Textbooks that relate to the papers. The aim is to put in Textbooks and assign certain textbooks to Papers so that a user can look up a Paper, see what textbooks there are for the course and click on them to see more textbook details.
2. First you put in all the Textbooks as a new flexinode page type (called Textbooks) with the appropriate fields.
3. Next you put in Papers as a new flexinode page type (called Papers) with appropriate fields, but this time you also want to have a field type that allows you to choose any of the Textbooks that have been entered using the Textbooks flexinode page type. This would be very similar listing to the Categories (previously Taxonomy) fields that would show up in your page type once you had created them under Admin/Categories. How would you create the Textbooks field in the Papers page type?

Would you have to write your own field type for the flexinode module that would allow this type of field to be added to flexinodes?

If anyone has done this or is thinking of doing it please let me know as I will do it otherwise.