You have probably used 'su' to become root. That's fine, but as such it won't modify your environment variables like $PATH (it contains the directories where executables are searched when you type a command in the command line); in other words, the $PATH is the user's and not root's, and regular user's $PATH does not include the sbin directories in which the administrative tools are. For example ifconfig and iwconfig are in /sbin which is in root's $PATH but not regular users'.
Fix one: run with full path
Fix two (easier if you run more than one command): su with dash
type in password as usually, and after this you get a root command prompt, and your environment is changed to that of root's (reverts back when you 'exit'). After this just
and it should be found.
If you are using Fedora 8, the graphical tools might make it easier to configure your wireless network.
