This is how i get working Mountain Lion 10.8.5 natively on Haswell architecture with ASRock Z87E-ITX

Since Haswell CPU is now natively supported by Mountain LION 10.8.5 it is very easy to get it running on PC hardware.

All you need for that is a legal copy of Mountain Lion 10.8.5 from the App Store, the patched BIOS for your Asrock Z87E-ITX Mainboard, Unibeast 2.1 and USB Stick with 8GB space.

Prerequisites:

• Asrock Z87E-ITX Mainboard
• I used for my project energy efficiency 35 Watt CPU: Intel i5-4570T
  My whole system is consuming only 22 Watts at mid range load in that combo!
• Mountain LION from App Store
• Unibeast 2.1
• PMPatched Z87E-ITX Bios
• 8GB USB Stick

Optional like my Low Wattage Setup:

• Chenbro Mini-ITX ES34169 Case with 4 x HDD Hotswap bay and 120W PSU included
• ADATA XPG SX300 Solid State Drive (Fits in mSATA Slot of Z87E-ITX awesome!)
• Kingston HyperX blu 16GB Kit DDR3 PC3-1600 Memory
• 4x WD RED WD10JFCX 2,5 inch 1TB SATAIII HDD WD10JFCX for my ZFS Mirror1 RAID. Fast but very low power consuming!

First of all we need to prepare our Mainboard with compatible BIOS which we can download here

Download and extract the content of the zip file to your USB Stick and plug it in your PC.
On boot up hit F6 and flash the shown Bios Update.

Now its time to prepare the Mountain Lion Installer USB Stick:

Insert your USB Stick to you Mac again and open the Disk Utility application.
Click on the USB Drive on the left pane then on the partiton tab to the right.
Choose:
Partition Layout: 1 Partition
Click Options choose: Master Boot Record
Format: Mac OS Extended (journaled)
then: Apply

Eject your USB Stick and reattach it to your Mac

Download Unibeast 2.1 from here and run it.

Choose your USB Stick as Destination and Choose Mac App Store Mountain Lion 10.8
Click continue and enter your password.

What is missing? Please comment to help! ...[go to source]