It's not possible. This is all that works.
Saw the asset package you uploaded, awesome upload. Ausgezeichnet!
However, Teancum I believe I am getting closer to getting the Xboc 360 data files into MUA! I am working with pak file format now, as I know it is encoded by the developers, so it is almost
possible ha-ha. For now, I have the entire 360 MUA II sound files (including the DLC content with Juggernaut) which I took easily out of the .pak file, ripped and converted to wav. These of course, I already implemented into MUA with zsm/zss editor so sound easily works.
Edit : .igz for the Xbox 360, not our typical igb as I presume you guys already are aware of. And the packages are still kept as .pkgb so that is really not a problem. Only a matter of Zeit, mein guter freund :p