Just for backup purposes as I need this tftp server only on-demand:

Setup Instructions

NOTE: By default, tftp-hpa listens to the tftp port specified in /etc/services (port 69)
on all local addresses.

To run tftpd manually for download only access, use this command:

sudo tftpd -L -s

To run tftpd manually and support tftp uploads, add "-c" to the command:

sudo tftpd -L -c -s

You may run tftpd at system boot using the startupitem if you installed tftp-hpa
using the server variant. To load the startup item using launchctl:

sudo launchctl load -w /Library/LaunchDaemons/org.macports.tftpd.plist

NOTE: When loading tftp-hpa using launchctl, make sure to place the files you want to serve
in /opt/local/var/tftp-hpa/, because that is the location set in the StartupItem.

If you wish to run tftpd in inetd mode, you may make an inetd compatible .plist
file and replace the one installed by MacPorts in /Library/LaunchDaemons. You
may use /System/Library/LaunchDaemons/tftp.plist as a template.