Open a text terminal (emulator console) and type:

sudo -i

or

sudo su

enter root password and follow the instructions below within the terminal.

Use a text editor such as leafpad or nano.

 leafpad /etc/apt/sources.list.d/liquorix.list

Add the following line

deb http://liquorix.net/debian sid main

Save and quit

Refresh package list:

apt-get update

Install keyring:

All packages in the liquorix repository are signed. Run the command below to install the keyring package for liquorix.net.

apt-get install liquorix-keyring

Install the kernel:

The Liquorix kernel can be installed by way of meta-packages. This will guarantee that the latest kernel is installed on every upgrade.

32-bit without PAE (HIGHMEM4G):

apt-get install linux-image-liquorix-686 linux-headers-liquorix-686

32-bit with PAE (HIGHMEM64G):

apt-get install linux-image-liquorix-686-pae linux-headers-liquorix-686-pae

64-bit:

apt-get install linux-image-liquorix-amd64 linux-headers-liquorix-amd64

On my system I also had to do

update-grub 

Open Menu→ System→ Sparky APTus tool.

Refresh package list.

Navigate to System tab→ Install Liquorix kernel. Follow the instruction.