For many NV mods, all you need to do to make them work in TTW is add them to the form lists for vendor chests of DC vendors, or the form lists for equipment for raiders or mutants or mercs. Maybe place a few in containers here and there. Be careful about adding them to general container lists or you'll end up with the items all over, and in places that make no sense. Example, I've seen weapon mods where you end up with three or four models in every mailbox.
In general, it's enough to add them to Moira's and Lydia's vendor chests. That gives you a chance to buy them no matter which DC house you end up with in the game.