Embed Widget, whitelist? config.xml?

I am trying to embed an external widget onto a tab in my app.
I have tried adding the code to an html object, adding it to an html page and embeding it from a html file on my server…
I think I need to add the source to the whitelist but cannot find the config.xml to edit.
Can you help please?
This is the code for my widget.

<script class="ai1ec-widget-placeholder" data-widget="ai1ec_agenda_widget" data-events_seek_type="events">
  (function(){var d=document,s=d.createElement('script'),

Hi, do you solve the problem? Mind to share?