Like Linux, our Java client works great in unattended mode on macs. It just isn't packaged easily, yet. We've attached the service definition file.
You'll need to modify the attached file for your installation, then copy it to the /Library/LaunchAgents directory.
You'll need to copy Elsinore.ScreenConnect.Core.jar and Elsinore.ScreenConnect.Client.jar to /usr/lib/
Then once you reboot ScreenConnect should run.
Let us know how it goes.