Maybe I am mistaken, but I believe Midi requires harware to run, not just something that can be emulated through a software layer.
Like with the soundblaster card for example it has a seperate MPU processor specifically for Midi. If Midi could be emulated that easily then Bochs would have supported Midi for all the old Dos games.
The XBOX does not have hardware support for Midi. There is really no point since none of the games would make use of it.
Regards,
KP