You can add the line including the full path to the sudoers file using "visudo" as root. Use the NOPASSWD option. This allows you to have the command in a script without prompting for a password. Enter the full exact command and use the full path to the command to run. At first glance, being able to run a root command without a password may seem like a problem, but if it is debugged (doesn't crash) and doesn't contain an escape (such as vi's ":!" or sendmail's shell escape), it means that you don't have to give other users the root password.
See man sudo and man 5 sudoers for more details.
As an alternative, use kinternet instead of a login script. You can scan for networks and authenticate using it.
Also, If your script isn't contained in /etc/profile.local but called from there, /usr/local/sbin would be a more logical location for it than /bin.
The Filesystem Hierarchy Standard contains an explanation:
http://www.tldp.org/LDP/Linux-Filesy...Hierarchy.html