Your mutant power is activated by pressing Y. You only have one use at start, or two if you're playing the USA version, but you can spend health to get as many as four. Just press it 5 times.
If you're in a hurry, you get a new use when you die, and have unlimited lives. Just spend all your health on this, die, and do it again.
Good Luck. If you need help/advice or advice for me, post a comment.