I had lots of problems with your code. Here is what I got to work.

use strict;
use Net::Telnet;

$b = Net::Telnet->new(
        Output_record_separator => '',
        Prompt => '/\$ $/',
        Timeout => 20,
        Host => 'localhost',
    );

$b->login("guest\n", "testme\n") or die "Connect failed: @{ $b->errmsg
+() }\n";

my @output = $b->cmd("who\n");
print "out @output\n";

@output = $b->cmd(q[
perl -w <<EOP
    use Net::Telnet;
    my \$c = Net::Telnet->new(
      Errmode => 'return',
      Telnetmode => 1,
      Output_record_separator => '',
      Prompt => '/\\\$ $/',
      Timeout => 10,
      Host => 'localhost'
    );
    \$c->login(
    "guest\n", 
    "testme\n"
    ) or die "Connect failed: @{ \$c->errmsg() }\n";
    my @output = \$c->cmd("who\n");
    print "out @output\n";
EOP
]);

print "out @output\n";
[download]

You need to change 'localhost', 'guest', and 'testme'.

UPDATE: did not have enought escaping. The prompt argument seems to be problematic.