I haven't GMed this module yet, but the spell seems pretty clear to me, so I'm unsure what you're looking for.
Are you asking how to run the confusion effect at intersections? RAW there's a 30% chance that when the party says e.g. "we turn left" they actually go right, and you describe what they see as they proceed in the wrong direction. The tomb doesn't actually have a lot of intersections, unless you count rooms with multiple exits as "intersections".
Such "messing with the mapper" mechanics don't really work unless the players are actually drawing their own map though. I usually run Kingmaker using an image of the map on a tablet obscured by a fog of war that I can slowly reveal, so that confusion effect is going to be a problem for me. If your players are good at separating their knowledge from character knowledge you could continue to reveal the true map while letting them know that their characters are confused about where they think they are, but if I take that approach it's going to be pretty hard for all of us to imagine what the characters think their map looks like.
The spell also has the choice of one of five extra effects, but the module says where that's used - in room D7, the Gust of Wind effect comes from Guards and Wards.