In this release, access to iLO hidden functions is expanded to iLO4 v2.77, released on December 17th, 2020.
This is the latest version that is able to support the commands used in previous versions. Work to patch v2.78+ versions of iLO4 has not begun at this time & is likely to be very complex.
Installation is fully documented in the readme. If you're especially daring, you can utilize the automatic installer. From a Ubuntu Live CD (I only tested 21.10 on 2/20/2022 - repos might break on other versions, especially with python2 as a dependency), you can run:
# make sure you turn iLO security off first! read the readme!
wget https://raw.githubusercontent.com/kendallgoto/ilo4_unlock/v2.77/automatic.sh
chmod +x automatic.sh
./automatic.shto install dependencies and flash your system. I only suggest doing this on a LiveCD booted directly on the server.