I did a Zweibel-turn in my 2007 XFC known routine
It is started on a vertical upline with negative snap rolls that you flatten out as the airspeed reaches zero. Then, input your upright flat spin controls and come right back down through your own smoke.
The guys with full size MX-2s do them really well by heading up in a right hand "shoulder roll", then flattening that out at the top and adding left rudder to come back down.
Think of it as a reverse blender. Loosely, the same controls but all about timing.
You all want a really good book, check out "The Four Minute Freestyle" by Xavier de Lapparent. Awesome resource on full size free manuevers.
Sorry didn't mean to jump in, just enthusiastic hehe... And I really like this maneuver.