At my school, we put the arm on the side where you're being choked on the guy's hip (assuming standing guillotine) and drape the other arm over his trapezoid. We've just been taught to then wait it out, because you physically cannot be choked out from this position (although with a gi, you might smother in his sleeve if you're not careful). This is a choke that takes a LOT out of the person applying it, so we simply wait until his bicep tires out and then pull our heads out of the hold. If he tries to go to ground, cross the arm on the side being choked diagonally across his body and grab the back of his knee. Pull and you will fall into side control (although your head will still be trapped). Again, you will wait it out and then pull your head out of the choke.