How to get a service working upon launch

You can make this work with launchd. This requires two steps: First creating a script that invokes your service(s), and second creating a LaunchAgent plist file that will call the script at launch.

First step: Creating a script that invokes your service(s)

1. Write a text file with the following content, where ~/Library/Services/myservice.workflow points to the service you want to start (if you want to start more than one service, repeat the second line pointing to the different services):

   #!/bin/bash
   automator ~/Library/Services/myservice.workflow
   

2. Save the file, e.g. as ~/Library/LaunchAgents/me.myname.launchmyservice.sh

3. Make it executable by issuing the following command in the Terminal:

   chmod u+x ~/Library/LaunchAgents/me.myname.launchmyservice.sh
   

Second step: Creating a LaunchAgent plist that calls the script

1. Write a text file with the following content. You need to adapt the string /Users/myusername/Library/LaunchAgents/me.myname.launchmyservice.sh so it points to the script created in the first step. You cannot use a relative path with ~.

   <?xml version="1.0" encoding="UTF-8"?>
   <!DOCTYPE plist PUBLIC "-//Apple Computer//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
   <plist version="1.0">
   <dict>
     <key>Label</key>
     <string>me.myname.launchmyservice</string>
     <key>ProgramArguments</key>
     <array>
       <string>/Users/myusername/Library/LaunchAgents/me.myname.launchmyservice.sh</string>
     </array>
     <key>RunAtLoad</key>
     <true/>
   </dict>
   </plist>
   

2. Save the text file to ~/Library/LaunchAgents/me.myname.update-desktop-from-webcam.plist – the name should match the "Label" key in the file.

3. Load it by issuing the following command:

   launchctl load ~/Library/LaunchAgents/me.myname.update-desktop-from-webcam.plist