You could have a look at PDF::Reuse::Barcode, Barcode::Code128, GD::Barcode.

The documentation is a little sparse, but after a bit of digging through the sources, I've managed to come up with something that at least looks like a barcode... :)

You probably want to play with the parameters.  Good luck!

#!/usr/bin/perl

use PDF::API2;

my $pdf  = PDF::API2->new();
my $page = $pdf->page();
my $gfx  = $page->gfx();

my $barcode = $pdf->xo_ean13( # EAN-13 type 

    -code => "0123456789012", # message

    -zone => 20,       # size of bars
    -umzn => 25,       # upper "mending zone"
    -lmzn => 15,       # lower "mending zone"
    #-quzn => 0,       # quiet zone
    #-ofwt => 0.5,     # overflow width

    -font => $pdf->corefont('Helvetica'),
    -fnsz => 12,       # font size

    #-ext  => 1,       # extended character set
    #-extn => '...',   # barcode extension
    #-text => '',      # alternative text
);

$gfx->formimage($barcode, 250, 400, 1);
                         # x    y   size (scaling)

$pdf->saveas("barcode-test.pdf");
[download]

(other available types are codabar, code128, 2of5int, 3of9)