How can I create or update an animation in script that works with Animator component?

I'm working on a game that uses sprite based animation and I've been looking into programmatically altering said sprites.

I want to merge different sprites together and change colors, etc. and I want to do all of that via a script. So far that's going well but I'm hitting a roadblock when it comes to altering a sprite sheet and then having it play on the animator.

Here is a further breakdown of what I'm trying to do:

1. I have an animator component on my game object that has an animation...

How can I create or update an animation in script that works with Animator component?