Ah. The problem is that when the developers made VX, they asked themselves "What would a player want to cast a spell on himself for other than to either heal himself or give himself a good status?". So they disabled the ability to do anything other than that to prevent a player from accidentally casting a bad spell on himself.
Your problem is that your spell does NOT heal the character or give a new status. Hence, your spell will always miss in battle (although the event should still work anyway), and it will not work at all outside of battle. As far as I know, there is only one solution to this: You have to make a wolf status.
Make the skill give you this "fake status" in addition to activating the common event. This will solve all of your problems, except that your spell would only ever work in one direction. You'd be able to turn into a wolf, but not be able to use the same spell to turn yourself back into a human again (assuming that your spell works both ways in the first place).
Edit: Just a thought, if you remove the "fake status" from your player at the end of the common event, you should be able to cast the spell on yourself again. This is all, of course, assuming that the same spell is used in transforming the player back from a wolf to a human.