Yea you can do that no problem, but you will still have to assign the directories and added any text to each one. If your server has the software and you configure 4images the thumbnails will be created for you.
I believe you upload your files to the media file, something like /4images/data/media be advised that i am not 100% sure. So try it out with one, remember you need to create your directories ... Hope that helps. Also after you upload go the the admin page for 4images .. and look for the photo you just uploaded.