This could be hard. Years ago, circa 2000, I played around with this. IIRC, only certain, early generation DVD drives were capable of region free play and only with a hard to find hardware hack(firmware update).
Once you had that, you needed a way to disable the way the MacOS DVD software player which locked itself to the region of the first disk you inserted.
I also did this on Windows - but at some point (Vista or 7), the OS team dropped support for the early generation DVD players. At that point, I gave up.
I have no idea if the current MacOS will still support them.