Well those files are MT32_PCM.ROM and MT32_CONTROL.ROM
MT32_CONTROL.ROM: go here http://vogons.zetafleet.com/viewtopic.php?t=7270
, read a little and you'll know how to build it(it's easy).
Put them in your scummvm folder, and select MT32 as device, the first time you run it it will take sometime to start, because scummvm is building the sound file, next runs will start as fast as usual.
To moderators: Legal situation of those roms are undertermined, as a previuos slashdot article, Roland was unable to demostrate that they own the rights of such roms, so to me, they're free until they can demostrate the opposite. If you think that you can have problems, simple delete the PCM link, but the other i think that it's legal.