The7 allows to use Font Awesome , as well as Fontello icons (fig. 1) :
You simply need to copy the code (e.g. <i class=”fa fa-smile-o”></i>) and paste it into corresponding field in a menu item (fig. 2.1) or a benefit adding/editing screen (fig. 2.2).
You can upload custom made fontello.com Icon Font through FTP to “wp-content/themes/dt-the7/fonts/fontello” folder, replacing the current ones.