Unfortunately you can't unless you cut into your screen. You will have to leave the top off of the tank (which of course raises the issue of how to suspend a flourescent light strip over the top of you tank.
Here is the answer - if you have a a flourescent light unit and not a bulb that that can be put into a clip on utility lamp all you have to do is get an appropriate sized narrow wire shelf (the ones that are sold in Home depot in the section were you can build your own closet organizers. These have a lip on the front of them. So if your tank is 24 inches long just get one that length and no wider than 12 inches. It will on the front of your tank (and not look bad at all really) and give you some space to fit the filter on the back. Inexpensive and it works.
Steve