how do i install a .kext file?

1.extract the zip to your desktop (not into a folder, literally to your desktop) this means there should be a file on your desktop called AppleNForceATA.kext
2. open Terminal, (/applications/utilities/terminal.app)
3. type sudo -s in terminal then your admin password following this, now you should be root.
4. type sudo mv /users/(YOUR USERNAME)/desktop/AppleNForceATA.kext /system/library/extensions
at this point the file AppleNForceATA.kext should have dissapeared from the desktop,
5. type sudo chmod -R 755 /System/Library/Extensions/AppleNForceATA.kext
6. type sudo chown -R root:wheel /System/Library/Extensions/AppleNForceATA.kext
7. now, CLOSE TERMINAL
then go to /system/library and look for
Extensions.mkext, and also look for extensions.kextcache,

TRASH BOTH OF THESE (dont worry theyll come back on nxt boot.)

8. reboot and hope it works

http://forum.insanelymac.com