The following command below install BitNinja and WHM plugin:
wget -qO- http://get.bitninja.io/bitninja-whm.tar.gz | tar -zx && ./bitninja-whm/install --license_key=[licensekey]
The other option is to install the WHM BitNinja plugin only:
wget -qO- http://get.bitninja.io/bitninja-whm.tar.gz | tar -zx && ./bitninja-whm/install --no_install_bitninja