How to install pfSense on a PC Engines APU2C4 board via console

This is a short how-to on how to quickly install pfSense on a PC Engines APU2C4 board. The video assumes some expertise in operating the command line, serial ports, identifying devices and using putty. The whole installation process doesn't take longer than 15 minutes. Requirements and assumptions: - UNIX-like OS. I have no idea how this is done in Windows. - A serial port, or a USB-Serial adapter with drivers installed. - A serial null modem cable. - Destination storage for the software: SD or mSATA drive. - Obviously, a APU2C4 board.