Locking Proxy On Firefox


I need to know if there is a way to make Firefox go through a proxy, and/or lock the proxy settings. I am trying to use a filtering service, and in order to work it requires that all traffic be routed through a proxy server. Obviously I can set for Safari and IE in the Network Preferences and lock the settings, but all someone has to do to get around it is download Firefox!

Any help is greatly appreciated.

I'm using Mac OS 10.3 "Panther"
See if this might work... download firefox, set its preferences, find where it saves its preferences, and make it read only. Try that.