Prerequisites:
How to add custom packages
Overview:
You can import custom .WAV files into your own package using an import statement
that is similar to the mesh, texture, and text import statements. You
do need to know how to set up your own packages for this to work, so please
follow the above link if you don't know how to do that.
NOTE: For the best trade-off between memory and quality, use 16-bit, 22k, mono .WAV files. If you need software for sound file editing and conversion, CoolEdit is a good choice and a "lite" version of it is available for $40. You can get that here: http://www.syntrillium.com/
I would recommend creating a folder called "Sounds" under your package folder for organizing your sound effects. Put the .WAV files that you're planning on using in this folder.
You'll need to either create an import .uc file just for importing your sounds, or add your import lines to an existing .uc file. If you have a lot of sound effects, it might make more sense to have a dedicated file for that.
Add an audio import line for each sound effect you want to import, like this:
#exec AUDIO IMPORT FILE="Sounds\Blaster.wav" NAME="BlasterFire" GROUP="Weapons"
The NAME is what will show up in the SoundFX browser and the GROUP will let you categorize your sounds just like you can with textures.
Exit out of UnrealEd if you're in it, delete your .u package file and rebuild it by going to an MS-DOS command prompt and typing "ucc make". Now when you run UnrealEd, your package file should show up as a choice in the SoundFX browser and you can now assign your custom sounds to things in your map.
NOTE: This method will build your sound effects into your .u package file. You can also create a .uax sound package file, if you don't want or need to use an "all purpose" .u package file. There doesn't seem to be an interface for creating those in the SoundFX browser, so you could copy/rename an existing .uax package and delete the redundant sounds from it manually. There *is* a SoundFX browser interface for importing .WAV files and saving the .uax file once it's set up.