Add captcha Popup to pages

I need a captcha popup window that occurs after a certain amount of PageViews or if the same IP has multiple session ids. The PHP code is in place to know when to trigger the captcha popup. The popup must use the existing jQuery library or just css or php. Coder must be proficient in PHP/MySQL to understand existing code. The project should be coded for both [login to view URL] and [login to view URL] (separate files) should we decided to switch captcha methods. This is not a simple form post, this will be a generated page, and must seamlessly integrate into the website. Please ask any questions you have.