Change the animation of the animation is possible, and yes you can create a slider for that. I found a tutorial for this here in the forum once, if I happen to find it I'll post the link here for you.
However, keep in mind 2 things.
1st, note that changing the HUE of the animation will change the color of the whole sprite, so it's not going to be a good idea if there are parts of the sprite that should remain the same. For instance if you want to change the color only of the shirt of a character, adjusting the HUE won't work. In this cases you will have to go through creating lots of sprites in different colors.
2nd, try and check if the device for which you are developing the game can handle the Fx effect for WebGL, it would be really bad if after all that work the colors couldn't change because of software limitations.