Wow old thread! What screw are you talking about? The two bolts close to the fender are pretty straightforward. The one on the tube with the maf just needs to be loosened. It's a metal clamp so just loosen it enough to pull the airbox out.
2015 320i xDrive | Imperial Blue Metallic/Black SensaTec | Sport Package | Lighting Package | Moonroof | Heated front seats
Past BMWs: 2006 330i, 2000 323i