Disabling Proxys in mozilla for *nix

Hi All,

 I dont know if this is the right place to post this but I was wondering 
what would be the best way to disable users from changing there proxy 
setting?

1. I know you can remove the edit -> prefences 
2. I have read that you can use pref_lock but I cannot seem to find out how 
to do that (If anyone has any documation please let me know)

is there any other way anyone can think of and of this which is the best

Thanks