battled this Mountain Lion for 2 days.
finally made progress in a combination of Boot DVD Mountain Lion off torrent, and ripped to change THREE important kext to enable 6870 to enter the installation phase.
Mountain Lion's vanilla
ATI6000Controller.kext ATISupport.kext ATIFramebuffer.kext
must be replaced by 10.7.4 to get you somewhere.
then booted using chameleon option: -v -x -F DSDT=NULL GraphicsEnabler=No
Booting and bypassing all the crap has been the toughest road, once you get into the installation, without just a white screen and a mouse, is darn straight forward for the installation. however, another big hurdle for me was to boot into ML using NO DSDT taking advantage of the UEFI with vanilla throttling and thermal management.
not using any of the beast stuff,able to get the 889 Audio to work by using osx86.net 's APPLEHDA.kext for ML. RT8111E's kext can be found in Realtek's site.
Wifi and bluetooth are apple parts OOB.
with no DSDT, everything you exp...
I completed two Mac Pro 2009 cases. and had started my third mod.
it only gets better. my aim is to leave the external and internal as vanilla as possible, that is not to cut anything unneccessarily.
will breifly list the pictures of my previously two mods.
will start a work log of my third mod from scratch here.
Continous update. Work in Progress.
Hope you will enjoy~
Z68MA, i52400, 4Gb RAM 1600, ATI 6670
My Mod #2 - a picture tells a thousand words, so i will save the comprehension.
GA-Z68MX, i7 2600K, 16Gb RAM 1600, ATI 6870, 10.7.4. + 27" LED ACD + G5 USB Keyboard, Bluetooth Keyboard, Magjic Mouse and TrackPad