The Coax Information Rogue Talent allows a character to use the Diplomacy of Bluff skills when bullying someone into being cooperative. But what exactly does the PC say in such a case?
Specifically: the Bluff skill has a lot of feats, traits and class abilities that improve specific uses of the Bluff skill - like lying, or specifically telling an outrageous lie, or hiding your intentions, or claiming to be innocent... et cetera. So it's rather significant to know what type of Bluff it takes to make someone "friendly" for 1d6 × 10 minutes. Does anyone know?
You use Bluff instead of Diplomacy, or you use Bluff instead of Intimidate. You aren't good at being either charming or menacing: you're good at lying.
How do you roleplay it? By roleplaying!
So how do you use Bluff instead of Diplomacy? You cozy up to them. You butter them up. You tell them you are an artist, and you think the security guard has a heroic profile, and you'd like to paint his picture. Then you get him to pose nude for you. You get him to practice posing while you go grab your #2 beveled tip paintbrush that you just left inside. You leave him there posing naked while you go rob the place (or something). After a few minutes, he starts to realize you played him. You run away, praying he will never catch up with you.
How do you use Bluff instead of Intimidate? Pretend to be a cop. Tell him he got a girl pregnant, and you were sent by her father to force you to marry her. As he starts to panic, you offer to pretend you didn't find him if he gives you a bribe. If not that, then some other piece of compromising information that is just plausible enough to make your victim want to settle instead of fight. The next day, he'll realize your story was crap, but by then it will be too late. And it's not like he'll go to the police: that would be an admission of guilt!
RAW, there is not a modifier based on the situation. You are making them intimidated by use of another skill bonus.
But if role play was the goal and if I remember my police dramas, you align yourself with their world view and convince them that they are right and the rest of the world is wrong. After that, you are working with them towards whatever it is that you need from them.
Depending on the opening, I would say no modifier if they think you might be like them or a -5 if they suspect that you have an ulterior motive. I would put a -10 if you were obviously working against their interest (like the cop in the interrogation room). These modifiers would apply equally in my opinion to when you are lying outright, or finessing the truth through diplomacy.
I wouldn’t go any further than -10 because of the way intimidate is set up. Intimidate is the much easier alternative in most situations where the NPC is hostile or unfriendly, so an ability that mimics it should be held to a comparable standard.