The easiest mod to do is the needlewheel mesh mod. That will let the pump pull a little more air. You are limited in the mods you can do with this skimmer because of the size of the neck.
If your not afraid to drill some holes in the skimmer body, you can make it a recirculating skimmer, which then can be run externally. It's not an easy mod tho as the holes must be precisely placed and uniseals put in to keep the new plumbing watertight. I wouldn't suggest this kind of mod unless you're not worried about destroying the skimmer. It's easy to crack the body while drilling it out.