Select Instant Action mode, choose your levels, but do not launch. Go to the options and choose the "Hero" selection. Change the options to the following: Best Player, 4 Points, and the time for the Hero to become available to 4 seconds. Your Hero or Villain can still die and the meter runs out, but you only need to kill four people for four points to unlock the Hero or Villain again. Also, if you get the points when you are playing as the Hero or Villain, when you die while playing as the Hero or Villain they still count as the points -- you can pick to play as them immediately.