Make the driver build and link on 10.7.
You will still need the 10.8 SDK.
Due to Apple removing GC, Xcode 4.6 is recommended.
This also meant that the System Preference bundle had to be GC-compatible, and ARC and GC don't work together.
Installation changes:
Force the kext modules to unload prior to deleting them.
Update the welcome text.
Restore the installation location to /System/Library/Extensions.