If you're using the packaged version, it's set up to use the integrated dosbox-staging MT-32 emulation rather than external MUNT - put your ROMs in the 'roms' directory, switch to MT-32 in the launcher and it should work!
If you're using WCAT in a custom DOSbox setup there shouldn't be any difference between stock WC and WCAT for MT-32...
The DOS zip also has a DOSBox-X config, but again that's set up for the integrated MT-32 emulation.
Hope that helps!