Dear munders,
the htaccess.txt file must have accompanied the quickstart package. However, if you cannot find it, you can take it from the latest Joomla 1.5.15 package and place it in your joomla root and rename it to .htaccess. At times in some of the hosting spaces, the .htaccess may not be seen (not sure why), it happened to me many times that i renamed the file and it vanished. Although i could see the file in the cpanel file manager.
Since, it is mesolite, with Virtuemart, in my case Virtuemart did not go well with the Joomla native SEO activation. So you may want to try any other 3rd party sef solution.
Regards,
Arvind