The only way I could think you could do this without a preset is if you went into the game and altered the eye textures themselves. Say if you added some kind of marking to the Normal eye texture- while it would put that marking on your character, if would also change the eyes for all characters (yours and everyone else's) with the Normal eye texture.
So, in short, without a preset, you sadly cannot make eye markings. Sorry, m'dear. o:
