Yes- it has been a while š You will need to modify the framework/shortcodes/testimonial-shortcodes.php file to output a HTML list instead of div elements. Then apply the [responsive_slider] shortcode to display the testimonials.
If you do not want to mess with PHP, you can grab the HTML generated by the shortcode (View Source in the browser), modify the DIVs to UL-LI elements and then use [responsive_slider] shortcode to display the elements, one at a time. Pls make sure you remove the column classes like fourcol, threecol from the generated HTML so that the testimonials occupy full width. Hope this helps.