Wilexa, thanks heaps for that — username@ftp.mydomain.net.au worked for me in the end.
However, now that I'm 'in', I can't seem to make any changes i.e. even though I logged in with username and password, I only have read-only priveleges, with no way to change those priveleges using 'Get info.'
Unless someone knows of a way to get around that, I'm just going to revert to using a third-party client for now. Perhaps one day when I acquire fingers of speed and a better knowledge of OSX terminal, I'll be able to do it all the old fashioned way (read: probably never ).
Cheers! —Jos