This file: /Library/LaunchDaemons/org.postgresql.dbms.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>Label</key>
    <string>org.postgresql.dbms</string>
    <key>UserName</key>
    <string>postgres</string>
    <key>GroupName</key>
    <string>postgres</string>
    <key>ProgramArguments</key>
    <array>
      <string>/usr/local/postgres/bin/postmaster</string>
      <string>-D</string>
      <string>/usr/local/postgres/data</string>
    </array>
    <key>RunAtLoad</key>
    <true/>
</dict>
</plist>