http://www.webmasterworld.com/forum88/7515.htm
http://curl.haxx.se/mail/archive-2003-05/0038.html
http://www.knowledgesutra.com/forums/topic/38162-automatic-login-using-curl/
http://www.bigresource.com/PHP-php-login-to-other-site-using-curl-ZbsunCYO.html
Намерих тези незнам дали ще станат, но ги разгледай...