There are numerous ways to create bootable USB installer for hackintosh, most of them are Chameleon based and Unibeast is just one of them. The installation process is quite simple if you bought your copy from App store. Download Unibeast and just follow tonymacx86 instructions and you are good to go. But you should consider that tonymacx86 is not an open source and therefore is not in OSx86 spirit. Also apparently he stole the code from qoopz , nawcom , AnV and few others that made the legacy kernel. Here is one great explanation why you should not use tonymacx86, and here is another.
But there is another way to install it and even more, it supports raw installESD.dmg instalation, it’s called myHack, it’s Chameleon based USB Instaler + after install utility. MyHack functionality is more less the same as Unibeast + Multibeast, just simplier and better…
When installing Mac OS X, it would be a good idea to use one extra hard disk drive for the installation, to preserve your old operating system, just in case something goes wrong.
You will need USB stick, minimum 8GB, all the data will be erased, so back it up if needed and format back after finish installation.
Also working OS X SL 10.6.8 or Lion is needed to make a bootable Mountain Lion USB. (if u don’t already have a working OS X and using Windows, you can download, burn and temporary install iatkos L1 ISO image (search torrents) and install it like shown on this tutorial (drivers selection depends on your hardware).
Second option, if you are using Windows is to install Snow Leopard or Lion on a virtual machine (Virtual Box), and run Unibeast on there instead. Virtualbox Extension Pack will be also needed to view USB drives from vm. This method will probably not work if your computer uses an Ivy Bridge processor.
With working OS X SL or Lion you can buy and download Mountain Lion from the App Store. If you’ve already bought it you can navigate to the Purchased tab and grab it from here. Once it’s downloaded the Installer will pop up but instead of running it just close it.
Use myHack to create your bootable USB installer