Ooops. Okay. You'd be doing all of your interaction from the Quest. All the script would do is activate the actor associated with the quest. You'd place that Actor in a holding cell somewhere out of sight. Then make your trigger. The script attached to that trigger would be something like:
Scriptname AskQuestionScript extends ObjectReference Message Property ActorProperty Auto Event OnActivate(ObjectReference akActionRef) IF (akActionRef == Game.GetPlayer()) ActorProperty.Activate(Game.GetPlayer()) ENDIF EndEvent
But as I said before I haven't done this. I'm not sure you can "activate" an Actor like this to get to its dialogue. There's likely probably something on Quest itself. Someone out there has to have done this before... hopefully they'll say something.

If not I'll check out what happens on the Oghma Infinium quest. I remember after talking to the old man in his house you get stopped by one of the dremora lords. It sounds like that's the effect you're looking for.