You might want to consider offering --performance as an option as well, this doesn't require a module to be loaded.
Localization too.
![Smile :-)](./images/smilies/icon_smile.gif)
The \n in your localization string doesn't create a newline on the terminal. This seems to work for me
*) echo $l_usage | sed 's/\\n/\n/g';;
It would also be nice to get a message at the end confirming that something had been done. Maybe something like
cpu scaling set
scaling govenor: ondemand
CPU frequency: 800MHz
excellent