Skillsystems DragonVein ability (Colorz + Circles) and Void’s Blitzarre Adventure (?) both import custom wav files and you can look into the code for either of them, so it’s been done and there’s some hints leftover at least.
(I haven’t figured it out myself but hopefully someone can illuminate the process. Currently stuck on Wav2EA parameters and how you would convert an .s to a .wav (if at all).)