I've been in contact with Soeren, the author of Virtuemart

VirtueMart is an Open Source E-Commerce solution to be used together with a Content Management System (CMS) called Joomla! (but also works with Mambo). Joomla and VirtueMart are written in PHP and made for easy use in a PHP / MySQL environment.

(see my forum entry here and his forum entry here). He has provided me some software patches, which will all make their way into securityimages 4.1.3 code (version to be release soon)