Will the slideshow run in a widget?

Congratulation! 😀

Basically is by add the slideshow shortcode to the text widget, but since widget is not accept shortcode, you can try this tutorial:

http://digwp.com/2010/03/shortcodes-in-widgets/

Or this one:

https://wordpress.org/support/topic/how-to-make-shortcodes-work-in-a-widget?replies=4