If you have 1.9, open the configuration for your tabbed dock and click on Size & Appearance. At the bottom, you'll see Entry Names. Select the one you want from the dropdown.
If you are using OD 2.0 beta, you can't do it (turn it on or off) from the configuration. If you create a new dock, it'll be there automagically though. If you didn't uninstall 1.9, you can unload 2.0 and then load 1.9. Do what I mentioned above and then click close. Unload 1.9 and reload 2.0 and you should be set.
