What OS are you using? FTP is old and long of tooth, not to mention not very secure if that is a problem in your case. On Linux it is easy to have the slave computer(s) do a NFS mount to the server. Windows also has a similar mounting system, but I don’t know if you need a special version of Windows or not. I can’t remember the name of the system, on Linux it’s called Samba.
Hi, Blender doesn´t “understand” ftp, better to use a network share as Grimm mention.
Every Windows version support network shares, you can use it as regular directory on every system in the same network.
If you’re on Windows (as you should be if you have to ask questions like this), you’ll want to use the builtin Windows (SMB) networking and mount a share as a disk. That way, you’ll be able to (more or less) use it like any other drive and most programs will “just work”.
If you’re on Linux, you can use SMB (Samba) or NFS. Also, you actually can mount FTP servers into the file system using something like http://curlftpfs.sourceforge.net/. There’s probably no good reason why you’d want to prefer that, though.