Another excellent question, tommyacquario. 🙂 This is also done with a template override. To that end, please make sure you’ve familiarized yourself with the Themer’s Guide, linked in the sidebar.
Then, you basically need to add a few lines of code to your wootickets/tickets.php file. Here’s an example of the modified file:
http://pastebin.com/rX1SYDsc
The code that controls showing the tickets available is on lines 92-94. You should be able to just slip those lines into your overriden tickets.php to affect the change.
Please let us know how it goes! 🙂