Setting up multiple textures for facial expressions on characters

Hey all, I was wondering, I have a character that I have modeled in Maya. and I have different textures I want to use for the face. These textures have different facial expressions.

I would like to setup these textures to swap based on what animation that is playing.

I understand that there are animation curves that can trigger material parameters. Is there a way to use these to swap between textures as needed?

I was looking for the same thing and stumbled across this:

Don't know if you still need it, but if it saves anyone else from smashing their face into the keyboard, I will be happy!

I need it with time function, or something else to animate mouth and eyes.