I'm not sure if this should be posted here or in scripting, because im guessing that's the easiest solution, but anyway...

I have an eye texture on a planar with animated Uvs. I have a keyframe animation but want to add very slight twitch movements without having to keyframe them.
I know very little about MEL, but i've tried adding a rand expression to the keyframed channels and i just get an error saying they're already controlled by something else.

Preferably i'd like the be able to toggle the movement on/off as well.

thanks for reading! all help appreciated