What I tend to do is caption the image, colour code it and then click save...
Well, I will note that you can also add the colour code with keyboard shortcuts in that dialog as well. (cmd-0, cmd-1, cmd-2 etc)
Mixed with adding captions and switching through fields with the tab key, you could accomplish the whole thing without ever resorting to the trackpad. For me at least, that is faster and more accurate.
-Mick