You can use PHP as a web client as well. You can use the cUrl library to make requests from PHP.
You can use setopt to set all kinds op options for your cUrl session, including POST (CURLOPT_POST
) and the POST variables (CURLOPT_POSTFIELDS
), but also choose a kind of authentication (CURLOPT_HTTPAUTH
) in case the site doesn't use normal post for this.
I found an example that might be useful here: http://davidwalsh.name/curl-post, although you can find many other examples by Googling for something like 'php curl post'.