How to add a user attribute to entire folder of documents?

[J-Mac]

I imported a folder full of PDF files. I also created a user attribute that I want to add to all of the individual info items (in this case, the PDF files). I can add them one by one, but I have several more folders to import so I would like to automate this if possible. I believe that creating a template from the Document template and adding this new attribute to it would help, but how do I properly import the folders using the new template? Or, perhaps using a template is not the best way? I'm hoping to get some advice before I get too far into this little project.

I would appreciate some advice on how best to get these folders and files in with my user attribute automatically assigned.

Thanks in advance,

Jim