How to free up specific Port(s)

I am trying to use port 69 for vncviewer in listen or reverse mode. My Verizon hotspot has limited pre-defined ports available for forwarding so I need to use either (53,21,80,119,110,25,161,23,69). New MacBook Pro Snow Leopard 10.6. Veteran Windows user...2 days with Macintosh. Any help is appreciated as I try to make this Macintosh meet my needs. Port 69 is preferred.

I should note that when I try to start RealVNC in listen mode using port 69 is fails, port 8080 and others allow the service to start fine.

On my system port 69 is defined as follows:

tftp 69/udp # Trivial File Transfer
tftp 69/tcp # Trivial File Transfer