Users that require the Legacy Kernel MUST follow step 5a
As the fifth update to Snow Leopard, 10.6.5 was released earlier today. 10.6.5 doesn’t really bring any noteworthy changes, though it’s wise to run the latest version of the OS. Apple also often requires the latest version to run certain software, so an upgrade should be performed for compatibility reasons. Snow Leopard continues to be a breeze to update and very few changes need to be made to the system to have everything running normal again. After the update, Audio and Wi-Fi will be broken, but they can be fixed in just a few short steps.
To update to 10.6.5:
1. Open com.apple.Boot.plist found in /Extra/.
2. Change pmVersion=20 to pmVersion=21 and save the file. (See example kernel flags here)
5. Install the 10.6.5 update
5a. Only for users that require the legacy kernel: Run the 10.6.5/10.5.0 Legacy Kernel package.
7. Kext Helper AppleHDA.kext and run a tag cache rebuild
8. Delete IO80211Family.kext from /System/Library/Extensions/
9. Reboot and enjoy 10.6.5