If I understand your question right, CGI.pm is definitly not the right thing for something like that. Check out the LWP (libwww-perl) man page.

I think you want to do something like this:

#!/usr/bin/perl -w 

use LWP;

print "Content-type:text/html\n\n";

$url = "http://www.blabla.com/cgi-bin/foobar.pl";

$ua = new LWP::UserAgent;
my $req = new HTTP::Request POST => $url;
$req->content_type('application/x-www-form-urlencoded');
$req->content('username=snowcrash&passwd=123456');
my $res = $ua->request($req);
print $res->content;
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