you need to get good or perfect. best place to do it is the Triceron (sp) building in the industrial district. just clear out henchmen and and start hopping. there is a visual and audio Q that should help you learn the rhythm. nonetheless that building makes it easy. --- I just want to get along. NO BIG DEAL!
I've also done this several times with nothing unlocking. Several hits, then whiplash, then more hits, then whip trip, all part of one combo. Obviously I must be missing something. Any ideas? --- "I have attained ultra speed by training, and training, and training, all while wearing 100-ton boxers!!!" - Mid-Boss (Disgaea)
The only help I can give is that it seems you need to hit more then one person within the move. Maybe try flip floping the order you do them in. I didn't get it my first time trying but I got it my 2nd so there's something special about it that we don't know about.