The following FAQ contains questions and answers on installing
and configuring Vm2Mage.  Can I use Vm2Mage on existing Magento
sites?  Yes, you can. Vm2Mage does not require a clean Magento
install. All products, categories and customers that are
migrated from VirtueMart, will just be added as new entities to
Magento.  Do Magento and Joomla! need to be installed in the
same place?  No, the migration using Vm2Mage is taking place
over HTTP, which means that Magento and Joomla! can be installed
on separate domains and even separate webservers. This puts down
the requirement that firewalls need to allow incoming and
outgoing HTTP-traffic and that domainnames can be resolved
properly on both environments.