How to patch the kernel
The vanilla kernel is located on your USB installer after running Unibeast. Here's how to patch it:
For Yosemite 10.10.x:in Terminal, assuming your USB is called Installer
After you install OS X to your HDD, you will have vanilla kernel on the HDD, leading to the same instant reboot problem. So, you must re-enter the OS X installer, and go into Terminal (using Utilities -> Terminal) and replace the kernel with the patched version: