Mouse trap for a squirrel?

How about a Hav-a-hart trap, and then remove him to the outside. Of course, you will have to take some measures to prevent him and his peers from reentering your home. You can sometimes find all of the little cracks by entering your attic during daylight hours, keeping the light off in the attic. Mark every single little crack (glimmer of sunlight) with spray paint so that you can seal them later. Hardware cloth works well for this job....they can eat through calking.