This took a little bit of time to get running mainly due to ET being a 32bit game, so here we go…
This was only possible through use of the sdl-sound patch created by these guys http://nullkey.kapsi.fi/et-sdl-sound/
After doing this you will have replaced the standard executable. That being the case, if you were to update the game through Desura your renamed et.x86 file will be replaced. As far as I could tell there is no method to edit the Desura launch paramaters locally. Editing desura_launch_Play.sh had not influence on the Desura client settings for the game, so this is the next best thing. Replace <desura install location> with the path to your Desura folder.
Install Wolfenstein: Enemy Territory through Desura
Open your terminal:
$ cd /<desura install location>/common/wolfenstein-enemy-territory/
$ mv et.x86 et.x86_org
$ wget -q -O - http://nullkey.kapsi.fi/et-sdl-sound/et-sdl-sound.gz | gzip -d > et-sdl-sound && chmod a+x et-sdl-sound
$ mv et-sdl-sound et.x86
$ chmod +x et.x86
$ nano et.x86
Edit the following in et.x86:
GAME_PATH="/<desura install location>/common/wolfenstein-enemy-territory"
GAME_BIN='et.x86_org'GAME_DIR='<desura install location>/common/wolfenstein-enemy-territory'
Now when you launch the game from Desura it will launch with sound enabled.
NB: My system was already setup as a multiarch system, to do this install the multiarch libs
sudo apt-get ia32-libs-multiarch