#!/usr/bin/perl

use strict;
use warnings;

use XML::LibXML;

local $/;
my $xml = <DATA>;
print $xml, "\n";

my $parser = XML::LibXML->new();
my $doc    = $parser->parse_string( $xml );
my $nodes  = $doc->findnodes( '/msg/text()' );
my $node   = $nodes->pop();
my $string = $node->data;
   $string =~ s/^As a last resort //;
   $string =~ s/is also/is extremely/;
$node->setData( $string );
$node->appendData( " ... and XML::LibXSLT too!" );

print $doc->toString();

__DATA__
<?xml version="1.0" encoding="iso-8859-1"?>
<msg>As a last resort XML::LibXML is also useful.</msg>
[download]

use strict;
use XML::Twig;
local $/;
XML::Twig->new(
  TwigHandlers => {
    '/root/msg' => sub { $_[1]->set_text('Twig is easy') }
  }
)->parse(<DATA>)->print;
__DATA__
<?xml version="1.0" encoding="iso-8859-1"?>
<root><msg>As a last resort XML::LibXML is also useful.</msg></root>
[download]

Boris