Threaded Paginate

Stumped on this one. i have an existing database i need to paginate using threaded (or best option you can think of). i manully went thru (350) products and categories and added the parent_id category_id but my problem is if this makes sense:

3 Top Categoreies (new, used, specials)

These have sub categoreies so thats now linked to the parent_id of the top 3. But these sub categoreies have sub_sub categories

so sub category has parent_id to top category and sub_sub parent_id is matched with sub category....

 

So user go to used/ i need to get all used products

used/cars/ pulls only used cars

used/cars/honda refines it even more

 

What is the best way to accomplish this and pass it to paginate?

 

Thanks,

 

Dave