I'm sure it depends on how much you modded. An actually hosted or pinned modification? Probably not, but don't quote me on it. A few edited folders you've done on your own such as the the unit or build prod folders, yes :D I've done it. It's the actually modifications that can't be done, because MTW VI was before mod switches' time. This like NTW, XL are overwrites. In other words, make a back up of your original MTW VI.