I fought my way through the instructions HERE
and eventually by brute force got it installed.
How I managed to install Liquorix
Click on Computer on Desktop >
Click on File System > etc >
Right Click on apt > Open as administrator >
Double Click on sources.list.save >
Copy & Paste all between the quotes "deb http://liquorix.net/debian
sid main" below the other entries > then Save
Open Terminal and Copy & Paste this in
sudo apt-get update
apt-get install '^liquorix-([^-]+-)?keyring.?'
Then open Package Manager and scroll down to Kernel and modules and click on it
If I've remembered all this correctly then you will see 4 Liquorix entries
I Right Clicked on each and Marked for Installation
Apply install etc.
Restart the Computer and hopefully that is it.
As someone who hasn't much of a clue what I'm doing the above may not be strictly correct.