Start with a Trapeze. Swing the yo-yo back off and use your non-throwhand middle finger to hold onto the string. Bring it all the way around your throwhand wrist and land onto both strings.

As the yo-yo comes down on the string, let go of it with your non-throwhand middle finger, and circle around the yo-yo with your throwhand holding onto the string. On the second pass, just as in Iron Whip help guide the string down and in towards the gap of the yo-yo.
Note: It is important to do this in one motion to keep up the momentum of the string spinning around the yo-yo.