I have installed on 2.3.1. It is really nice and working.
Im using qtpro4.6.1
http://addons.oscommerce.com/info/888
Dated on 7 Dec 2010
The only thing have to remove one } on product info page. (install instruction no. 20)
<?php
}
//++++ QT Pro: End Changed Code
to
<?php
//++++ QT Pro: End Changed Code
FYI: Get screenshot folder from qtpro4.6