There are two options you can take as I see it :  

1. MacPorts (formerly DarwinPorts)

2. "Build" from "source"  

This guide assumes the following :

* Downloads go to your desktop

* You have installed X11 & XCode tools and all that jazz from your OSX 10.4Install disc

* We will call your user name "uname" for this guide

* The $ symbol denotes a new line input in terminal and should not actually be entered, just whatever follows it  

OPTION 1 : MacPorts  Download macports from : http://svn.macports.org/repository/macports/downloads/MacPorts-1.5.0/MacPorts-1.5.0-10.4.dmg

Mount and install the dmg file. (note that during the actual physical install to disc, macports seems to hang for a while, this is because it is updating all its sources and such, just let it go)

You now have to add /opt/local to your $PATH. I usually do this thru vi, I will do my best to explain how to do this thru terminal :  

$ sudo vi /etc/profile

Arrow down two spaces to the "PATH" line and hit Shift+A this will bring you to the end (if /opt/local is already there, refer to the last line in this paragraph), arrow over left once, and add :/opt/local This should all be within the ending quote mark and should look something like this :

PATH="/bin:/sbin:/usr/bin:/usr/sbin:/opt/local" now hit Esc then Shift+; then wq! then enter

Close and open a new terminal window and type the following :

sudo port -v selfupdate

sudo port -vc install aircrack-ng

After this is done doing the damn thang, you now have aircrack-ng installed.

$ aircrack-ng in terminal to get a list of commands

OPTION 2 : "Source"

Download aircrack : http://download.aircrack-ng.org/aircrack-ng-0.9.1.tar.gz

Un-tar/gzip it by double clicking on the file

Open the folder and rename the Makefile to Makefile.old

Rename the Makefile.osx to Makefile

In terminal :

$ cd /Users/uname/Desktop/aircrack-ng-0.9.1

$ make

$ sudo make install

You now have to add /usr/local/bin to your $PATH. I usually do this thru vi, I will do my best to explain how to do this thru terminal :

$ sudo vi /etc/profile

Arrow down two spaces to the "PATH" line and hit Shift+A this will bring you to the end (if /opt/local is already there, refer to the last line in this paragraph), arrow over left once, and add :/usr/local/bin This should all be within the ending quote mark and look something like this :

PATH="/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin" now hit Esc then Shift+; then wq! then enter

After this is done doing the damn thang, you now have aircrack-ng installed.

$ aircrack-ng in terminal to get a list of commands