[Plugin: HL Twitter] where do I make shortcode changes

I would like to add a keyword follower, along with my user follower, to my HL Twitter widget. I see the information about the shortcode syntax, but I don’t see where I can change that in the WP control panel or in the actual code. I can only add a ‘user’ in the WP control panel.
Thanks

http://ww.wp.xz.cn/extend/plugins/hl-twitter/