Dorian can secure it through letters and so on, as easily or with as much difficulty as you'd like.

Being horribly human-centric and currently unaware that ancient elven history has any connection to Corypheus or future dangers, the Inquisition leadership on the whole isn't going to be willing to devote much time or any money to this endeavor. That said, no one but the ex-Circle archivist will fuss if Dorian trades some of the more useless books in the library for others, and Dorian may be able to charm and/or annoy a small amount of money out of Josephine in the name of building the Inquisition's library into an impressive and unique collection that will impress visitors and attract scholars etc. etc. etc. as long as no one mentions that any of the books at issue are banned.