Ideally, from what i have learned by following Espio is that he finds the codes, for NPC's actions and basically adds or replaces those codes with your character of choice. I think he also re-adds the character onto the field so that you can basically give them those specific codes to follow the leader. (like the guy in the desert prison, or aeris when escaping the church.)
I couldnt really give you any technical terms (which i think you were looking for) but I think Espio also likes people to find things out on there own using trial and error methods like he does. =)
what i can say is i think the tool youre looking for is the Makao reactor? which helps you edit things in the FLevel.lgp file