i think it should be inserted in some critical choice , so the interaction could be only a few, 3 per chapters at max i think (because we won't see a lot of it due to the amount of extra work it represents) and to make it work the players need to be near the conversation and click on it to be place to the area where it could happen.
i think it could be moddable but it will require a lot of skill not only on the dev part. It will be a + to the game, i don't think i ever saw that in another crpg, unless it is in a persistant world mod of nwn2 where you can have something close to it implemented by the gamemaster.
