He is in a basement shop in the building right next the sewer entrance to The Thieves' Way.
Head to The Obelisk of Lost Souls and get to The Keeper of Nihility's room 2nd level of dungeon ( 47,566,453 ) . At least one member of your party will need to have completed the quests, Entrance Into the Obelisk and Summoning the Creator to access level 2 of the Obelisk (unless you are high enough level *unsure of level required* that the doors will automatically be unlocked, but at the required level of this quest, you should be able to get through without doing the OoLS access quests. The devs removed the requirement for ALL levels to do it some years ago).
Inside the Keeper's room, click any of the tapestries
Search for a tapestry representing Bayle. Walk near the one with a Claymore on it.
Search for a tapestry representing Eylee. Walk near the one with a Mandolin on it.
Search for a tapestry representing Fiddlezip. Walk near the one with an Overall on it.
Search for a tapestry representing Kruzz. Walk near the one with a Fork on it.
Search for a tapestry representing Asharae. Walk near the one with a Robe on it.
Search for a tapestry representing Kaltuk. Walk near the one with a Robe on it.
Search for a tapestry representing Nurgg. Walk near the one with a Shield on it.
After you run into each tapestry to update the named Ethernauts, it asks you to find a hidden tapestry. The update is behind a broken stone pillar near the entrance to the Keeper's room. Keep running around the pillar until you get the update. Find the missing one behind the name.
Go to North Freeport, 3 Compassion Road and run next to the house to zone into The Nasin Manor Library where you must kill Troyer, a level 83^^^ guard (Note: The 12-22-2008 HotFix removed the requirement that all members of the party be on this step. You can now zone in so long as at least one member of your party is on this step of the quest.)