I don't see why you'd need a script-- what did you have in mind? A losing battle, or just falling over during a cutscene or something?
For a battle, you could easily create battle events where on a given turn, the enemy does some attack that will inevitably take out a party, or simply inflict status "Down" on the entire group-- just be sure to check the "Continue even when loser" checkbox. (Don't forget to heal the party to some degree afterwards, though...)
Did that help, or did you have something else in mind?