Requirements
Intel Mac running OS 10.7 Lion or later.
Properly set up ftpusers and ftpd.conf (probably set up if you used ftpd under Snow Leopard)
Must be run from an admin account.
Must enter admin account password when you run the app.
General FTP setup and FTPD help
To enable ftp in the terminal, it turns out all you have to do is start it. In the bash shell, all it takes is...
%sudo /usr/libexec/ftpd -D
And to stop ftpd all it takes is...
%sudo killall ftpd
A user commented on MacUpdate and pointed out perhaps a better way to do this is to tell launchctl to load the ftpd deamon on demand. This means it won't show in the process list when ftpd-enable looks for it so the padlock would stay red. But when somebody tries to connect via ftp, the ftpd deamon will automatically start.
The following terminal command can be used to enable ftpd. It doesn't start ftpd, so nothing shows up in the task list. But when somebody connects to your Mac via ftp, ftpd starts up on demand and keeps running for up to a minute after the connection drops.
sudo -s launchctl load -w /System/Library/LaunchDaemons/ftp.plist
To disable ftpd, you remove it launchctl. A better method might involve leaving it loaded but get rid of the -w switch that overrides the disabled flag Apple put in ftp.plist but I'm doing it this way for now...
sudo -s launchctl unload -w /System/Library/LaunchDaemons/ftp.plist