i've seen something similar on the web before, and from what i understand, if done properly, works quite well.
if the water is fed from the tank, ran through the skimmer, then into a resivoir with a return pump, you ensure that all of your overflow water is being skimmed.
i think the key, is to havea really good powerful air pump and stone, to inject a good amount of bubbles into the skimmer.
one thing i might consider if i were to try something like that, is to get the water moving in a circular motion, and have it enter more at the top, then at the bottom. the motion could be generated by simply putting an elbow on the end of the water line. and having the airstone all the way at the bottom.
this way, the water is moving down and the air is moving up, like greg suggested.
you'll probably also want a gate valve on the exit hole, to maintain a good water level in the skimmer.
i'll attach a drawing of my modified idea..
note: i've never done it, jsut thinking it through and trying to help improve the plan
