The article on setting up a Pi Powered PVR with OSMC is great.
Just a heads up that we recommend sudo apt-get update && sudo apt-get dist-upgrade -y, sudo apt-get upgrade can cause problems (as new dependencies are not captured). You can also update via My OSMC > Updater.
I'll make sure that the firmware you reference in the article makes it in to a future version of OSMC
Also: OSMC itself is not quite based on Raspbian. The ARMv6l (Pi 1) version is, but the Pi 2 / Pi 3 versions are based on Jessie upstream. You could say that as OSMC is a Debian based operating system just like Raspbian, it has the full package repository.
Sam