At night go to the road area and look around and eavesdrop on Scar. (Note: this happens after the bandits attack bareshed)
Ok so (just got done playing through it another time) you have to at least have met jester till you were able to speak with him freely. Go to the track at night and you'll eavesdrop, (I guess it is random) go back to jester and exhaust all of the dialogue options then the next day you'll ba able to begin infiltration (which is basically the battle with tank and scar)