Here i will explain how to install Litespeed webserver in WHM.
According to the Litespeed wiki :

1.Open & login to your SSH terminal

2. Execute this command to download the installer :

wget http://www.litespeedtech.com/packages/cpanel/lsws_whm_autoinstaller.sh

3. Next we will make the file executable :

chmod a+x lsws_whm_autoinstaller.sh

4.Last step we can execute this command :
(please check the litespeed wiki for parameter explanation)

./lsws_whm_autoinstaller.sh TRIAL 2 1000 admin a1234567 root@localhost 1 0

If you have litespeed license, replace “TRIAL” with your serial number.
You can replace “admin” with another litespeed admin username.
You can replace “a1234567 ” with another litespeed admin password.
You can replace “root@localhost” with another litespeed admin e-mail.

5. Wait until it completes.

6. A new sub menu named “Litespeed Web Server” will appear on your WHM.

7. You must activate litespeed from that sub menu.

• To buy new litespeed license, click here.

• Source : xrvel