How to add others libraries such as Zenpen to WYSIWYG profiles? I would like to use an editor for Drupal like Zenpen. Is it possible to add that library (Zenpen) to WYSIWYG profiles?
You'll need to write a WYSIWYG module plugin. Here is an example module you could follow.

Here is a simple .inc from the WYSIWYG module itself. Wrap your Zenpen one in a module like Ueditor (above) and you're done.