These directions fro a Mac OS X startup file were contributed by a Mac user.

1/ Create a directory called /Library/StartupItems/noip2 
	if it does not already exist.
2/ Create a file called StartupParameters.plist in it
	with the following contents:

{
    Description     = "No-IP Dynamic DNS Update Client";
    Provides        = ("No-IP Dynamic DNS Update Client");
    Requires        = ("DirectoryServices");
    Uses            = ("Disks", "NFS");
    OrderPreference = ("None");
}

3/ Create a file called noip2 in it with the following contents:

#!/bin/sh

##
# No-IP.com Dynamic DNS Update Client
##

. /etc/rc.common

StartService ()
{
    ConsoleMessage "Starting No-IP.com Dynamic DNS Update Client"
    /usr/local/bin/noip2
}

StopService ()
{
    ConsoleMessage "Stopping No-IP.com Dynamic DNS Update Client"
    for i in `noip2 -S 2>&1 | grep Process | awk '{print $2}' | tr -d ','`
      do
        noip2 -K $i
      done
}

RestartService ()
{
    ConsoleMessage "Restarting No-IP.com Dynamic DNS Update Client"
    for i in `noip2 -S 2>&1 | grep Process | awk '{print $2}' | tr -d ','`  
      do
        noip2 -K $i
      done
    /usr/local/bin/noip2
}

RunService "$1"