What are your intentions? Just the FMV audio? All the audio including comms and PA/Gameflow audio? I'm assuming you're looking for a language other than Engligh, French, or German.
Not trying to be rude but are you familiar with how the games store the audio files and the audio tracks for the videos? There's basically 3 separate systems for audio and they basically would have different levels of difficulty based on how 'perfect' you want the dialogue to match the video.
The basic PA audio, and generic comms audio would be simplest since Most of those have either no video or a video that doesn't show mouth movements and then they just reuse the same head with different audio lines. You could just record the audio and swap out the files (provided you know how the game handles modified TRE Files and so one
For the other comms you would need to make sure to preserve the file length to match the video file and that would make recording audio a little more tricky as you would have to match pacing etc, unless you mimic the done-on-the-cheap dub styles that just don't bother and where you can still hear the English audio in the background.
The FMV files for cutscenes would be a ton more work as you would have to edit entirely new audio tracks for the videos that line up correctly. WHat's more, there isn't really dialogue free tracks available with the caveat that often dialogue is center mixed so you could remove one of the channels (maybe) and add your dialogue in and it might be okish.