Hi, mbrooks!
Thanks for your question regarding the Call to Action and Widget options. You can actually add a Widget in the Call to Action Area, by following this guide. That guide provides instructions for modifying Widgets in general, as well as inside the Call to Action. Widget placement is restricted depending on the theme. You would need to utilize CSS in order to customize the placement of the Widgets.
In either case, you could create a text Widget inside the Call to Action and place your shortcode (for the slider you create) in that text area. I hope this helps!
Sincerely,
Carlos E