Solving an "wireless tools not found" error from airmon-ng tool

Unfortunately, airmon-ng is not working on OS X, you will probably have to use a virtual PC with a linux OS + USB WiFi dongle. From FAQ:

Is Mac OS X supported?

The aircrack-ng suite has limited Mac OS X support. Currently it only supports the following tools: aircrack-ng, packetforge-ng, ivstools and makeivs. Any program which requires opening a wireless interface is not supported.

I traced it with dtruss and it is looking for the iwpriv command which is part of wireless-tools package on Linux systems (commands like iwconfig, iwlist, etc)

Output from a Ubuntu server box

mike@jarvis:~$ aptitude show wireless-tools
Package: wireless-tools
State: installed
Automatically installed: no
Version: 30~pre9-3ubuntu4
Priority: optional
Section: net
Maintainer: Ubuntu Core Developers <[email protected]>
Uncompressed Size: 463k
Depends: libc6 (>= 2.7), libiw30 (>= 30~pre1)
Description: Tools for manipulating Linux Wireless Extensions
 This package contains the Wireless tools, used to manipulate the Linux Wireless Extensions. The Wireless Extension is an interface allowing you to set Wireless LAN specific parameters and get the specific stats.
Homepage: http://www.hpl.hp.com/personal/Jean_Tourrilhes/Linux/Tools.html