an XML::Twig example to help bootstrap you:

use strict;
use warnings;
use XML::Twig;
my $twig = new XML::Twig('pretty_print' => 'indented');
$twig->safe_parse('<say/>');
my $root = $twig->root();
$root->set_text('Hello World');
$twig->print();
[download]

The fine documentation should be read if you're going to use it. I haven't met a problem with XML that twig couldn't handle though.