If you have an early 2008 MacBook Pro, or a Revision A MacBook Air (like me!), Engadget shown that they can be hacked to support the 4-finger swipe gestures of the October MacBooks and Revision B MacBook Air.
Unfortunately, the original hack required you to reinstall Leopard, using an installer CD from one of the newer MacBooks, and was also quite complicated, involving editing .kext files and fooling the Leopard installer into thinking you had a newer MacBook.
Fortunately, with the release of OS X 10.5.6 the hack has become much simpler, and I’m happy to report that I’m providing an edited .kext file that will enable this on Early 2008 Mac Pros and Airs.
- Update to 10.5.6, via Software Update or you can also download delta and combo updates from Apple.
- Download and unzip the .kext file which is attached below.
- Navigate to /System/Library/Extensions/ and copy the fileAppleUSBMultitouch.kext to a safe location (a backup copy)
- Delete the AppleUSBMultitouch.kext file in /System/Library/Extensions (You will have to authenticate).
- Move the modified .kext file from Step 2 into /System/Library/Extensions/. (You will need to authenticate again).
- Open Disk Utility (in Applications–> Utilities –> Disk Utility) and click “Repair Permissions” (This will take a while to complete).
- Restart your computer
After the restart, navigate to the trackpad system preferences pane, and 4-finger gestures should be enabled. With 4 fingers, swipe up/down for Expose, and swipe left/right to switch applications.
Source : thebws.com/blog/brandon