I think I figured out how to get the PartfFinder app to work to my benefit. I downloaded the csv file entitled year, make, model, type and then put everything in alphabetical order and added a column called category and subcategory. Basically, you just have to organize the information as to how it will display on your own site. I create my main category and then placed all the categories created by the app underneath the main category. Then it's as simple as creating two new columns in the file, labeling them category and subcategory. I have tested it out and it seems to be working. 

Maybe give this a try and let me know if it works for you too!