попробуй отослать такой запрос

POST http://localhost/joomla/index.php HTTP/1.0
Accept: */*
Referer: http://localhost/joomla/
Accept-Language: ru-ru
Content-Type: application/x-www-form-urlencoded
Proxy-Connection: Keep-Alive
User-Agent: Mozilla/5.0 (compatible; MSIE 5.6; Windows NT 5.1; SV1)
Host: localhost
Content-Length: 215
Pragma: no-cache
Cookie: mosvisitor=1; 2a92fbec41de02cdc3501c558a1726f7=-

username=login&passwd=password&remember=yes&Submit =%C2%EE%E9%F2%E8&option=login&op2=login&lang=russi an&message=0&force_session=1&j7a960116fc3c3148f217 b6fa8f88ed45=1