[Plugin: MarcTV Comment Quicktags] Add more buttons

I have this plugin version 1.5.3 and WordPress version 3.2.1.

I have one question. Is it possible I add a new button? I want to add image link, so people could add code [img]url[/img]

Thanks you 🙂

http://ww.wp.xz.cn/extend/plugins/marctv-quicktags/