A digital monitor to connect to the integrated graphics (HDMI connection works for sure)
An OS X machine with an empty PCIe m.2 SSD drive and some other drive that OS X is installed on (I used a Broadwell NUC with OS X on the 2.5" drive)
A PS/2 keyboard and mouse
(Optional) a supported PCIe network adapter, or a USB drive with Ubuntu Desktop 15.10 in order to move files on or off the machine if you don't have the network adapter (the onboard Ethernet works under Ubuntu)
Procedure
Boot to OS X on the other machine
Download El Capitan from the App Store
Partition the m.2 SSD into two or three parts: 9 GB JHFS+ for UniBeast (named, e.g. "Installer"), a FAT partition for copying files to/from Linux if you don't have an Ethernet adapter (named, e.g. "SHARED"), and a large JHFS+ area for the OS X install (named whatever you want)
Install UniBeast 6.0.x to the m.2 SSD. Select UEFI BIOS and leave all the graphics options unchecked.
