Dope Sheet-Make localScale jerk to a certain position rather than smoothly transitioning

I'm trying to make a monkey character for my game that just sits on a platform and moves back and forth, and I'm using the Dope Sheet. I'm trying to get the monkey to slide across the platform by putting the start position on a key in the start of the animation and the end position in the middle and the start position again at the end again so it would move smoothly back and forth. But I want the monkey's transform.localScale to be flipped at the middle and flipped back at the end. The problem I was having by simply putting a localScale key in the center with the scale flipped was that the monkey was slowly flipping throughout the animation, when I wanted him to just suddenly flip in the middle. Is there a way to have him just suddenly flip in the middle with the dope sheet animation?