For this example, I'm creating a simple Single Player map. When the player hits a trigger, it'll play a sound. I've set up three different triggers in the sample map:
trigger_once
trigger_damage
trigger_use

Feel free to use anything you need from this tutorial.

The .iwd file includes:
the radiant file
the map's .gsc file
the map's soundaliases file
and some sounds to be played

Suppliment

Installation/Testing:
Get the "zzz_sound_tut.iwd" out of the "Armors_sound_tut.zip" file. Place the zzz_sound_tut.iwd in your Activision/callofduty2/main folder. Start up the game, and in the main menu (with the console enabled) type "/map sound_tut" and press enter. To unistall the tutorial package, just delete the "zzz_sound_tut.iwd" from your main folder.


Just a word about the sample map:
If you look in the .csv file, you'll notice that the damage trigger's sound (sound3) has a min and max distance value of 500, while sound 2 and sound 4 (the once and use triggers) have a value of 150 and 300. This is because if you give a trigger_damage a low distance value, the sound will not be heard from far away. When you get closer to the trigger and want to shoot at it, it will not work because you allready shot at it when you were out of earshot, so it will appear that it does not work, when in reality all you needed to do was shoot it when you were close to it (close enough to hear it).

So I adjusted the distance value so that you can hear it no matter where you are in the small sample map. Feel free to adjust anything you want for your purposes.

Also, the .gsc file has wierd stuff like:
yellsoundtrig = getent ("sound2_trigger","targetname");
The yellsoundtrig is from a map I'm making. You can insert whatever you want in there, it doesn't seem to affect anything.

A word on sounds and soundaliases:
Sounds can make an average map and turn it into a professional map. The usage, timing, and locations are all factors that make or break great maps. Learning when and where to put sounds will take time and experience, but sounds are not hard to create.

This is how the COD2 sound system works:
A line in your .gsc file will reference a soundalias. A soundalias is just a fancy word for "sound name". Say you want to play a sound and it is called "mortar_fire_map_duhoc.wav" or something like that. In your .csv file (the soundalias file) you will place a name next to the "mortar_fire_map_duchoc.wav". You could call it like, "mortarfire" or something. So in your .gsc file you could reference the sound without having to type "mortar_fire_map_duhoc.wav". All you need to put is "mortarfire". So for example this could be a line in the .gsc file that refernces the sound:
guns playsound("mortarfire");

The .csv file stores this information:
-what the sound's nickname or "soundalias" is -so it can be quickly referenced by that nickname in the .gsc file
-What the sound's file name is and where it's located, for example "misc/sound2.wav"
-And then it has information on what channel the sound is to be played on, volumes, distances, etc...

The .gsc file referenced the nickname of the soundfile, and the .csv file see's that nickname, and then has a bunch of information on the sound file, like volumes and stuff, while the .gsc file tells the game when it is appropriate to play the sound. If you have a trigger, a sound file, a .gsc file, and a .csv file, you can make it happen.

I hope that this has helped somebody!
-Armormaster