This tutorial from libreboot.org will show you how to get FreeBSD set up on a libreboot system. Libreboot is an alternative BIOS/UEFI for bootloading your operating system. Follow the link below for the full set of instructions.
How to install FreeBSD on a libreboot system
This section relates to preparing, booting and installing FreeBSD on your libreboot system, using nothing more than a USB flash drive (and dd). They’ve only been tested on a Lenovo ThinkPad x200.
It is expected that you use text mode in libreboot (txtmode images), for the early boot process in FreeBSD. Booting the installer results in a red flickering text display, and doesn’t boot.
Thanks go to ioxcide in this Reddit post for the initial instructions.
TODO: test FreeBSD more extensively, and make sure it works (and fix it if it does not). Instructions are provided here, to boot and install FreeBSD but we’re not sure whether it is currently fully compatible with libreboot.
Full tutorial: https://libreboot.org/docs/bsd/freebsd.html