I found that it is actually this simple:
- (from Windows) copy the .jar from the first line in this post to the openHAB2-conf Samba share.
- on the box just do a sudo cp /etc/openhab2/org.openhab.binding.zwave-2.3.0-SNAPSHOT.jar /usr/share/openhab2/addons/ . The binding will restart itself. Check with bundle:list | grep -i z in karaf.
- if you have also upgraded the OH2 snapshot and the binding doesn’t become Active, chances are you need to do a feature:install openhab-transport-serial in karaf.