You can install PHP-Nuke on your account via the automatic script installation system - Softaculous.
Here is the way of installing Mambo from Softaculous:
cPanel --> Softaculous --> Content Management --> PHP-Nuke --> New Installation
PHP-Nuke: One of the most popular community-based portals with a big choice of modules and languages.
For more information on auto installing scripts, visit the Softaculous article.