I'm here from DD-WRT forums.
Good news!
Because orange, who probably succesfully improved the script for Atheros not available anymore, and his script too, so I decided to ask, what is the problem. So this script is originally developed for Broadcom, not working on fon2100.
I asked Kadigan (on freenode IRC) who corrected the issue with reading SSID-s, so it's works very well now, but need to solve the joining problem. This requires atheros-specific commands, that is not known for us.

Here is the link for the script: drive(dot)google(dot)com/file/d/0B2WZkI4RAYK0LUpBMk5KMEFKcmc/view?usp=sharing

Very thanks for any help!