Logging in via SSH (Root Terminal) on the Linux server
1) Add debian third party repository to /etc/apt/sources.list
echo "deb http://ftp.de.debian.org/debian squeeze main non-free" /etc/apt/sources.list
2) Create a temporary installation directory:
mkdir /root/plesk
cd /root/plesk
3) Download the plesk auto installation script from parallels
wget http://download1.parallels.com/Plesk/PP11/11.0/Debian6/parallels_installer_v3.12.0_build120601.16_os_Debian_6.0_x86_64
chmod +x parallels_installer_v3.12.0_build120601.16_os_Debian_6.0_x86_64
4) Start the installation of Plesk:
./parallels_installer_v3.11.0_build111102.17_os_Debian_6.0_x86_64
5) Follow the menu-driven screen.