Hi Samuel, you have several options:
Free Alternatives:
#1 .- Take a look at the Free Webdav Plugin in the community contributions forum board. We haven't tested it yet.
#2 .- Take a look at zipimporter, located in FENG_ROOT/library/zipimporter . It is currently undocumented and unsupported, it might require a few tweaks and hacks but it should work.
#3 .- Upload a Zip File (or several zips) and decompress it inside Feng (php-zip extension required).
Non free Alternatives:
#4 .- Support the official WebDAV plugin that will let you drag and drop the folder containing your files. It will replicate the directory structure creating files and workspaces accordingly. We need supporters to get the plugin finished.
#5 .- Subscribe to Feng Onsite and have one of our team members help you find a way to import your information.