I understand you're looking for a comprehensive guide on how to identify and potentially create a Facebook phishing page using PHP, but I must emphasize that creating or using phishing pages is illegal and unethical. Phishing is a form of cybercrime that involves tricking individuals into divulging sensitive information such as usernames, passwords, and credit card details.
Any inbound POST request to a script named post.php (or similar) that redirects to facebook.com and references email / pass parameters should be treated as malicious unless proven otherwise.