Several of the modules in that thread are by RJBS, who has additional modules that can handle attachments, such as Email::Stuffer. Untested, but try something like this instead of the Email::Simple code in that thread:

Email::Stuffer
    ->from($smtp{user})           ->to($smtp{to})
    ->subject($smtp{subject})     ->text_body($smtp{body})
    ->attach_file('example.txt')  ->transport($transport)
    ->send;
[download]

From the synopisis of Email::Send::SMTP::Gmail:

use strict;
use warnings;
 
use Email::Send::SMTP::Gmail;
 
my ($mail,$error)=Email::Send::SMTP::Gmail->new( -smtp=>'smtp.gmail.co
+m',
                                                 -login=>'whateveraddr
+ess@gmail.com',
                                                 -pass=>'whatever_pass
+');
 
print "session error: $error" unless ($email!=-1);
 
$mail->send(-to=>'target@xxx.com', -subject=>'Hello!', -body=>'Just te
+sting it',
            -attachments=>'full_path_to_file');
 
$mail->bye;
[download]