Getting Started
We need first to add the main Linux Mint 12 repository to your repository list. So, open the terminal and run this command to edit /etc/apt/sources.list:
sudo gedit /etc/apt/sources.list
At the end of the file add this line:
deb http://packages.linuxmint.com/ lisa main upstream import
Save your file and close. Then, run this sequence of commands:
sudo apt-get update
sudo apt-get install linuxmint-keyring
To install the GNOME 2 Fork 'Mate' desktop, run now these commands:
sudo apt-get update
sudo apt-get install mint-meta-mate
Log out the current session, and at the login screen, select MATE, then login normally:
Scrennshot of the desktop:
Source: http://www.upubuntu.com/2011/11/how-to-install-gnome-2-fork-mate.html