The Uplifted Library is now accessible, hence the name uplifted I suppose.  Within the walls are Tritons and Boulders galore.  Finding your way around isn't difficult, its a single room with several ascending floors.  After  you have gone as far to the top as you can you will find a podium with a button.  Once pressed you will lower an elevator that you can use to gain access to the "attic" where the chest containing the Book of Khel is located.

You also need to acquire Lich Jars for any necromancers in the party.  These can be found in the Mad Necromancer's Lab in Shadowspire.  They are all over the lower section in several chests found there.  You will have more than enough to accomplish the Promotion.

Once you return the book to Vetrinus, he becomes an NPC and Lathaen in the House of Lathaen (#12 on the Twilight map) handles any future promotions.