Check out NativeTech website for information on how to do this and links to those who use these in their crafts.
NativeLanguages link has photos
But I was unaware that Italian porcupine quills were handy in bookmaking (no, not off line betting but in making a book).
David Warren has a nice essay about this.
One uses them to tamp curls and corners upon carefully shaped drops of glue; they will intrude wisely into edges recessed against raised borderings. They will compress with a precise amount of force. One quill, or another, will answer to each need. But these are makeshifts compared with the fine tooling of gold leaf; with working colour over the gold; or fixing minute particles of pigment in a consolidant. Whether in the conservation, or in the creation of an illuminated manuscript, icon, or altarpiece — should the job happen to require skill — the porcupine quill comes into its own.
a related essay on CherylPorter's porcupine quills discusses the use of Italian porcupine quills in repairing old books.
NatGeo article on Porcupines includes this fact on why they are so hard to remove:
more on the quill's biological properties here on Science: the barb makes them easier to penetrate but harder to remove.
Quills have sharp tips and overlapping scales or barbs that make them difficult to remove once they are stuck in another animal's skin. Porcupines grow new quills to replace the ones they lose.
so unles the dog has only a few quills, the advice is to get your vet to remove them: usually this is done under general anesthesia.
the article is graphic so only check the link if you have a strong stomach.