I assume that you are using LWP::UserAgent to do the server communication. If you're not doing this, think about doing this. The only drawback of LWP::UserAgent is, that it is not in the Perl distribution, but we have may documents in the monastery detailing how to install modules (even if you don't have administrative privileges) - use the Super Search and search for module and install or something like that.

If you're using LWP::UserAgent, there is the module HTTP::Cookies and the method $agent->cookie_jar() of your useragent. Just get the cookie jar from the useragent, fill it with the right cookie(s), and that would be it.

As an additional extra, you get proxy support for free with LWP::UserAgent.

Here's some untested code to manipulate cookies of UserAgent :

use strict;
use LWP::UserAgent;

use vars qw($ua, $request, $response, $cookie_jar, $URL);

$ua = new LWP::UserAgent;

# Read proxy settings from the environment, if given
$ua->proxy();

$request = new HTTP::Request($URL);
$response = $ua->request( $request );

$cookie_jar = new HTTP::Cookies;
$cookie_jar->extract_cookies($response);

# Tell $ua to use our cookie jar :
$ua->cookie_jar($cookie_jar);

# Make our cookies persistent
$cookie_jar->save("cookie_jar");

$ua->cookie_jar($cookie_jar);
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AgentM Systems nor Nasca Enterprises nor Bone::Easy nor Macperl is responsible for the comments made by AgentM. Remember, you can build any logical system with NOR.

The example given in the node above yours did mostly that. Set $URL to the URL that sets the cookie, and the LWP stuff will request it via a user agent of its own, noting the cookies and saving them for future reference. Follow up that example code with code that actually posts your form.

See the documentation for the LWP::UserAgent and, say, HTTP::Request stuff.. examples are extensive.