This Should work on any version of Linux.
the first thing you need to download the 32bit installer:
Next Browse to the installer in the terminal, and run this command;
chmod +x et-linux-2.60.x86.run ---This will make it so you can run the installer
Next we will run the installer in 32 bit mode:
once it's installed, it will ask you if you want to 'Run Now'
Type 'N' for No,
next Right click on your desktop and click 'Create Launcher'
under type choose "Application in terminal"
under name type:
'Wolfenstein - Enemy Territory'
and under command:
if You want the cool icon, open '/usr/local/games/enemy-territory' in a file browser
and drag 'ET.xmp' to the image of the spring board (in your create launcher window)
On your first launch You will be given the profile setup screen, if you change the screen resolution here your pc may freeze but after a reboot the game will run fine.
and you will be able to change the screen res from in game.
Note: if you are NOT using Ubuntu, you may NOT be able to create a launcher, so instead you will have to create a 'Shortcut' or 'Link' but under 'Command' You still use the same command that ubuntu users do.