I had made some changes so the component could work with cakePhp 1.3,
or at least it works in my application. The original article is
here, download the latest and the code i have modified.
Make sure you have:
1. Copied the component file into your app/controllers/components.
2. Copied the view file into your app/views/element/
3. To use "captcha_code" field form input.
You could "diff" to see what changes i had made in the code,
specially the component file. Hope it helps.