If you have a Mac, can use a friend's Mac or have a virtual machine running OSX then I highly recommend you use that, since you need an OSX system to make the USB stick to install it on your computer.
Download Mountain Lion from the App store, and also download myHack and follow the Guide. You will need an 8GB or larger USB stick to do this.
Then get these drivers for your board after you have come to the desktop:
Ethernet: ALXEthernet (use Kext Utility to install this by dragging the extracted kext onto the window.)
Sound: VoodooHDA (I use 2.8.2, unzip the ML version and install the pkg.)
Graphics: Should work OOB with 'Internal Graphics Memory Size' in BIOS set to 64M.
And about the multibooting... If you're installing on a different hard drive it does not matter what order you install the operating systems in. However, I would highly recommend you make the OSX hard drive the first boot option, since chameleon scans for different operating systems, where as Windows and Linux require you to enter them in manually.
Hope this helped!