you DON'T use FTP to transfer the songs
(unless you really wanted to, which would be silly & difficult).

As far as "Difficult", I agree there.
There is no tool for this, currently.

But it definately would not be silly.
Considering throughput over FTP is at least doulbe
that of file transfer rates using emplode or jemplode.

I bet someone here could make a tool that allowed you
to FTP your directory structure in to a given folder say: /drive0/temp/
that would appear in emplode or jemplode.
Then you could just move the files into whatever playlist structure you want.