WordPress Reviews plugin, BUT only for specific categories

Hey everybody.

I am working on expanding my WordPress-powered Website and I came up this very nice plugin:
https://www.dangrossman.info/wp-dg-review-site-1.1.php.txt (just one *.php file)

It basically turns your Worpress site/blog into a review site. So far so good and everything works. BUT the problem is that it literally turns your WHOLE site/blog into a review site.

I would like to change this, so it only works with specific categories (for example only for category “reviews”)
Unfortunately my PHP knowledge is rather limited.

Now I am not asking for someone to rewrite the whole plugin (even though I certainly wouldn’t mind ?? ), but it would be nice to get some clues or ideas or opinion about this.