Unfortunately, .NET code is currently the only way to create and mount these virtual hard drives from Windows Azure. But luckily, IIS7 has this integrated pipeline model which Windows Azure is also using. Among other things, this means that services provided by managed modules (written in .NET) can now be applied to all requests to the server, not just ones handled by ASP.NET.
Fortunately for PHP developers, these "other services" also include a PHP running as a FastCGI instance in your IIS server. He shows how to use this connection to your advantage and reach a mapped Azure drive through the Azure Drive HTTP module (the code's included for that, too). You can find the code he shares in the post and other handy PHP+Azure related tools on the PHPAzureContrib.com site.