This assumes that Serviio is installed under /Applications

Save the following piece of code in a file named org.serviio.server.plist

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
   <key>Label</key>
   <string>org.serviio.server</string>
   <key>ProgramArguments</key>
   <array>
      <string>/Applications/Serviio.app/Contents/MacOS/JavaApplicationStub</string>
   </array>
   <key>RunAtLoad</key>
   <true/>
</dict>
</plist>

and copy the file to where it will be launched on system start

# sudo cp org.serviio.server.plist /Library/LaunchDaemons/

and to start it right away

# sudo launchctl load /Library/LaunchDaemons/org.serviio.server.plist

and to stop it

# sudo launchctl unload /Library/LaunchDaemons/org.serviio.server.plist

Media library update fails unless you are logged in with the GUI due to the java image library tries to connect to a window server. By adding the following property to the Info.plist found in Serviio.app/Contents the java image library works without connecting to a window server.

                       <key>java.awt.headless</key>
                       <string>true</string>