There are a couple of different ways you can add titles. You're correct, the item_id column adds the title option for characters that possess that particular item. There are also a couple of quest objects that you can use to add titles using the perl system:
Code:
$client->SetAATitle(txt, save = 0)
$client->SetTitleSuffix(txt, save = 0)
can both be used to give a character a title. If you enter a value of 1 as the second parameter, it will save the title to the database as an option for that specific character in the titles window.