Joomla is a PHP CMS. I program in Perl and PHP and I'm a firm believer in saying that just because you can write in both doesn't mean you should!! In any one system it is best to stick to as few languages as possible, ideally just one.
Someone has mentioned Catalyst, which is a MVC system/framework rather than a CMS, but it may be a good starting point for including older scripts. There are Perl CMS systems built on top of Catalyst, but since I haven't used one I can't make recommendations.
If you spot any bugs in my solutions, it's because I've deliberately left them in as an exercise for the reader! :-)