Both this post and the one in FAQ's Lack the information to make DW TAB display. The FAQ url ->
http://forum.x-cart.com/viewtopic.php?t=17274
The files from this thread and the FAQ post are different, niether post explain that you have to edit the Tags.xml file and add a section and then if you what a Smarty Tab to appear on the tool bar you have to add code to insertbar.xml
While this is the same subject material as the post in FAQ the files this post point to are different and since there is no means to add to a FAQ post this is a good location to try to get DW to work with Smarty/X-Cart...