Similarly to master131's old releases for MW2 and MW3, I decided to figure out how to extract sounds from the COD4 fast files. The format is exactly the same, interestingly enough.
With some help by him to figure out the header structure fully, here is the full archive with all wave sounds found in all COD4 PC fast files, with proper RIFF headers, correct channel number and samplerate. Or at least all I could find by simply searching for .wav ;)
Oh, and one more thing: The playback speed/pitch is different in the game for some files. Refer to the soundaliases in the mod tools to figure out how much slower the file (or faster) is actually played ingame (for example the AC130 105mm fire sound is much slower ingame than the source wav file is).
The rest of the sounds is available via easy extraction from the iwd files and the mod tools.
Like him, I uploaded it to google drive since it's larger than this forum would allow for attachments (the archive contains only wav files):
Unlikely that you're going to be able to do anything. I tried around a bit with BO1, and while COD4 is not as "sophisticated" as that fast file format, I'm pretty sure it's unmoddable unless you are able to create the same fast file from scratch (with d3dbsp etc).
I'm not even sure of replacing one file with a file of the same length with includes something different would work. It might, but I changed soundalias names and filenames in BO1, rezipped it, and the game still knew which file to play. So yeah. Just for use with mods or whatnot.