[sir_pudding]

You could generalize the rules for influencing the PCs into something like the penalties from inflicted control, and maybe have some way they affect NPC reactions. So influence in this case would be:
Attack roll=Influence Skill
Defense Roll=Will-based skill "parry"; other than Mental Strength, I am not sure what skills would be useful here generally, a case could be made for Diplomacy or Public Speaking, I suppose.
Damage roll= Influence Points or something, maybe based on IQ based "thr" with Training bonuses based on skill.

IP would inflict penalties to defense, and probably distraction penalties for simultaneous tasks or could be spent to make a modified Reaction Roll for NPC or to penalize actions for PCs.

I certainly wouldn't be very comfortable with using such a combative system for non-hostile interactions, though.