Faster way to create bookmarks?

Good morning,

I have been searching the web for a better solution for creating bookmarks.

I have a PDF file I created which is 300 pages long. Some of my PDF's get 2000 pages. I started making bookmarks for the document, but it is very time consuming. Below you will see an example of of my table of contents, which is how I would like to make my bookmarks. It would be great if I could create the bookmark content in excel or some other program, and then import it into XI Acrobat to setup the actions.

Does anyone know if this is possible?

1. Item A

     A.Item under A

          i. Folder B under item A

               a. Item in folder B

2. Item A

     A.Item under A

          i. Folder B under item A

               a. Item in folder B

3. Item A

     A.Item under A

          i. Folder B under item A

               a. Item in folder B

I get pretty indepth with my bookmarks. And I am looking for a faster way to build it.

Thanks,

Dave