couchpotato launchd plist (goes in /Library/LaunchDaemons, then launchctl load -w com.couchpotato.plist ; launchctl start com.couchpotato)

com.couchpotato.plist

<?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>UserName</key>
    <string>ben</string>
    <key>Label</key>
    <string>com.couchpotato</string>
    <key>OnDemand</key>
    <false/>
    <key>ProgramArguments</key>
    <array>
        <string>python</string>
        <string>/Users/ben/plex/CouchPotatoServer/CouchPotato.py</string>
    </array>
    <key>RunAtLoad</key>
    <true/>
    <key>WorkingDirectory</key>
    <string>/Users/ben/plex/</string>
    <key>ServiceDescription</key>
    <string>CouchPotato</string>
</dict>
</plist>