I know there's a plugin called Alpha Mask that very handily takes in a greyscale image from clipboard or file, and maps the alpha channel on a layer based off of the value of pixels in the grayscale mask.
I was hoping for a tool with a similar function, taking in a greyscale image from clipboard or file, then changing the hue value of each pixeldepending on the value of the pixel in the mask. However, I don't really know where to look for something like this? Where can I find one?