#!/usr/bin/perl --

use strict;
use warnings;

my $xml = <<'__XML__';
<?xml version="1.0" encoding="UTF-8"?>
<?xml-styleshet type="text/xsl" href="stylesheet1.xsl"?>
<?xml-styleshet type="text/xsl" href="stylesheet2.xsl"?>
<?xml-styleshet type="text/xsl" href="stylesheet3.xsl"?>
<config />
__XML__

use XML::Twig;
my @style;
{
    XML::Twig->new(
        twig_handlers => {
            '?xml-styleshet' => sub {
                my ( $t, $pi, $data ) = @_;
                push @style, $data;
                return;
            },
        },
    )->parse($xml);
}
print join "\n", @style;
__END__
type="text/xsl" href="stylesheet1.xsl"
type="text/xsl" href="stylesheet2.xsl"
type="text/xsl" href="stylesheet3.xsl"