After a day of frustration with getting ALC892 working i finally managed to get it going. FYI i am no expert, merely the blind leading the blind.
In a clean install of Yosemite i have no audio or audio devices showing in "System preferences/Sound". I went into "/System/Library/Extentions" I Deleted "AppleHDA.kext" "AppleHDA892.kext" "realtekALC.kext". Then i went into /Library/Receipt/ I Deleted "com.tonymacx86.AppleHDA-892.pkg.bom" and "com.tonymacx86.AppleHDA-892.pkg.plist".
I then emptied my trash can, restarted computer then ran MultiBeast - Yosemite 7.0.0 where i installed /Driver/Audio/Realtek ALCxxx/ and checked ALC892. Then click build then click on Install. After Successful install reboot the computer and use the bootflags "kext-dev-mode=1" once back into Yosemite goto /System Preferences/Sound and select internal audio. Bingo you should have sound, at least thats what worked for me, Good luck!
Question for anyone who knows i have <string>kext-dev-mode=1</string> in my "org.chameleon.Boot.plist". Clearly i have typed it in wrong as i am forced to type "kext-dev-mode=1" at boot. How should it be properly formatted?