disk usage via ftp

If I were to issue the command 'du -h'
on my *nix systems, I get some nice output
detailing what directory(s) are hogging all the space.

How can I get a similar output only having FTP
access to a server? I had half thought about
doing a ls -lR and whippingup some Perl
to parse that mess out, but there must be a better way?

v/r
-Mike