you have to do one of two things....

1) you can create a brand new texture for the two faces, and animate as before .

2) if you only want to do one texture, you're going to have to map whatever it is, then create a succesion of frames from yellow to blue in the desired area. Then you have to go back into maya and use the 'movie' texture (which is a little misleading, cause it only takes still frames).

Seems most probable that you'd be best served using the first one. anybody else know a different method?