some guy on GAF said to use the RB+back+Y with the sword to launch the dog and then use the whip to keep him in the air... i already skipped over it by the time i read that so i haven't bothered trying it yet, but it doesn't seem like it'll work.
those type of challenges are just annoying, since you will need to do them EVERY TIME you do a scoring run since they count as verses in the chapter. at least DMC has the courtesy to make those strange challenges a one-off to get a health piece from or something. challenges like survival, kill during witch time, kill with torture attacks, etc. i'm fine with since they involve actual combat, not this stupid head-jumping nonsense.
then again the scoring system is fucked so who cares anyway