Here's a brief example:

#!/usr/bin/perl

use strict;
use warnings;

use Net::Telnet;
my $t = Net::Telnet->new(
                         Timeout => 10,
                         Port => 80
                        );
$t->open('www.google.com');
$t->print('GET /');

my $line = 0;
while (my $o = $t->getline())
{
    print ++$line . '. ' .$o;
}
[download]

Instead of port 80, you'd use port 6666. Instead of www.google.com, you'd use the real server. Instead of printing GET /, you'd do whatever starts the flow of information (which may be nothing - if so, remove that line). Instead of printing the line inside the while loop to STDOUT (the default), you'd print to a filehandle that you opened prior to the while loop, and you'd flush the filehandle after each write. So, something like this, which, unlike the above, is untested:

#!/usr/bin/perl

use strict;
use warnings;

use Net::Telnet;
my $t = Net::Telnet->new(
                         Timeout => 10,
                         Port => 6666
                        );
$t->open('mydataserver') or die "Can't connect to mydataserver: $!";

open my $fh, '>', '/tmp/file' or die "Can't write to /tmp/file: $!";
$fh->autoflush(1);

while (my $o = $t->getline())
{
    print $fh $o;
    # or $fh->print($o);
}
close $fh;
[download]