Any decent hardware store (and some not-so-decent stores) will have long-shank T15 screwdrivers. I have even seen some longer interchangeable bits that might work. The upper screws are into plastic, the lower screws are into the metal frame near the logic board. All the ones I've taken apart have yielded to slaps on the side and shaking about 1" above a padded surface, but for a while some of the cheaper "Mac cracking" kits looked like they came with a "stationary clip" (the ones with the semicircular spring around sheet-metal jaws).