It came from the Desert doesn't work with the Roland option. I get no sound at all, neither from the Windows Softsynth nor from my MT-32. I guess it must be some issue with the emulation of the MPU-401. I tried with DosBox 0.61 (and CVS).
I forgot, but it makes no difference. I have to add that I lack any install program belonging to the game but replaced the Adlib driver with the Roland driver in the game configuration file manually. So perhaps something isn't configured right then.
However, it tends to break other games so a better solution will have to be made. MPU-401 Manual says that status bit for the data queue is connected to irq input line and I always suspected that all commands should trigger irq by filling the data queue, but didn't have a game to figure this out exactly (others worked with only reset command tied to irq).
It works very well with "It came from the Desert". Sadly, Cinemaware didn't put much effort into the PC version so the sound is still inferior to the Amiga version.