If you really want to be sure, you can just bring your whole party into the room after you've gotten past the dialogue point where she checks - she doesn't care after that. Generally, the easiest way is to go in with the talking character, let her close and lock the door, then have the rest of your party jump across the broken wall section, into her area. They can all sneak right up to her and wait until you finish the dialogue and start the combat encounter. Save before you talk, and just make sure you get enough people with an initiative roll ahead of her to drop her before she gets a turn; that would be the 'smooth and in-game' way to do it, without skipping dialogue scenes or barrel-bombing the place.
