I did it last week, following these instructions: https://github.com/openmediavault/openmediavault/issues/1710Main problem I experienced was that mdns / bonjour name resolution stopped working, per the comment in that github issue, but OMV is working better than ever. I also upgraded to OMV7 at the same time, so I was pretty impressed that things transferred reasonably.
I believe OMV has instructions for this on their site, @salbang. It should definitely be possible.