I've just merged support to create MSXDOS format discs (720k DSDD discs)
This can be used from two different ports:
zcc +cpm -subtype=msx -create-app
Will create a CP/M program that thanks to the ABI compatibility will work in MSX-DOS
zcc +msx -subtype=disk -create-app
The disk subtype has been extended to additionally create a 720k DSDD disc image.