I hate to sound like a wet blanket here, but this doesn't really sound like a mechanical check at all if you don't want it to be.
You wet blanket, you!
It's clever players being clever. There's no real reason not to let them be clever as long as the role-playing is tight and the action at the table is flowing well.
I've been at tables where entire interrogations were simply roleplayed out, no dice needed. As long as the game's not breaking horribly because of a glib player, and as long as the table's gaining entertainment value from the proceedings, it seems perfectly fine to let a clever player Burn Notice his way in or out of an ostensibly secure facility.
But I've also been at tables where shy players, who really want to play the smooth talker, could really use a mechanical system to simulate what their characters can do that they themselves can not.
Right. And to be the other end of the spectrum of Bill, I literally have a (soon-to-be, if he passes his boards) board certified psychiatrist at my table. I need mechanics to keep IN CHECK when it comes to social interactions at times. lol.