This is another technique you can execute after securing the two-on-one.
Step foward your opponent, turn your hips away from him and then pull on his trapped arm while thrusting your leg between his two legs . This forces him off balance and onto one foot which allows you to reach down with your free hand and pick his planted foot out from underneath him.
Try to commit your hips while executing this technique : jump into your opponent, bump him with your hips and follow with ankle pick .

You can execute this technique from many other tie-up situations

This is a demo but with no ankle pick

http://www.themat.com/CoachesCorner/technique/MuleKick/default.php