Mate, excellent welcome post thank you.
I'm thinking of putting together a sound mod myself as thats what I'm into, so if i use this bit below it should be fine?
You'll see a list of files (weapons, explosions etc) now let's say you want to install gun sounds. Export weapons.ivaud to your desktop (or any other location) open it up with gta-ivaud. Now you can import sounds 1 by 1 or .. you can replace the entire weapons.ivaud if a mod provides it (if so .. you can skip the exporting and just import the new weapons.ivaud).
I've got the importing of mods ok now so hopefully I'll be able to produce a decent sound mod for myself and if its any good i'll post it up for the community to try.