OS X: Run script (or app) on a post-upgrade reboot

I'm trying to find a programmatic solution for a friend of mine, who operates a Hackintosh system, or OS X installed on non-Macintosh Intel computers. Whenever he is installing a Mac OS X security update, he needs to re-patch his audio drivers using MultiBeast. So, I was thinking about doing this automatically, given that Apple offers a way to hook a script post_upgrade (which I'm unaware of).

1. Create a file with the following script:

#!/bin/bash

CURR_VERSION="$(sw_vers -buildVersion)"
PREV_VERSION="$(cat ~/.previous-version)"

if [ "$CURR_VERSION" != "$PREV_VERSION" ]; then
  # Do stuff here

  echo "$CURR_VERSION" > ~/.previous-version
fi

2. chmod +x it
3. sudo nano /Library/LaunchDaemons/version-checker.plist
4. Type in:

<?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>version-checker</string>
    <key>ProgramArguments</key>
    <array>
        <string>/path/to/your/check_version.sh</string>
    </array>
    <key>StartInterval</key>
    <integer>60</integer>
    <key>RunAtLoad</key>
    <true/>
</dict>
</plist>

5. Save with CTRL+X, Y
6. sudo launchctl load /Library/LaunchDaemons/version-checker.plist