Pick the download you need. You'll find instructions on each page.
Captcha script
I wrote this little script because the gbook was filled up with junk every night.The captcha prevented this very well so I'm offering it for download.
It's very easy to integrate in any page you'll like.
In the captcha.php you can or even need to set the path of the fontfile.
You can even change the font- and the background color to match your own website style.
Download the captcha script