Following a kext installation, repair permissions then simply delete the obsolete Extensions.mkext along with the kernelcache in the /System/Library/Caches/com.apple.kext.caches/Startup directory then reboot.
The kernelcache will be automatically regenerated by the system upon reboot.
Just for reference, here are all the latest files (kexts, plists and DSDT) needed to viably boot and operate the XPS M1530 under the OS X 10.8.x
Thanks a lot, where do you put the extensions? If I compare to the first post only FakeSMC goes to /Extra/Extensions