Huh? FTP allows multiple file transfers with mput local-files. Or, you could install the fireftp extension on Firefox, select the files to transfer and say go. gary
"backend" is remarkably vague, WHICH back-end software are you running... or are you actually saying there's something with that vague a name?!?
I recommend uploading your files via FTP (File Transfer Protocol). A reliable FTP client that I use is FileZilla, which works flawlessly by connecting to your site and allowing you to upload and download files to the desired directories. Just make sure you upload the files in the correct plugin folder.