[Plugin: WP-dTree] Request: or patch if possible?

I’d like to have the dtree archive only show the archives of one specific category (need to show image galleries by year from category “exhibitions”). I have been using the category tree for the past couple years to achieve this, but, would really love to not have to list every year as a category, as it’s very cluttered and a hack. I believe it could easily be achieved with a slight adjustment in the arc-functions.php file, but, my php skills aren’t up to the challenge. Anybody?