enforce screensaver for all users of a system?

[Matt Morgan]

We're migrating some of our users to FC3 from Windows (yay!). In
Windows, we use system policies to force password-protected
screensavers to turn on after a certain amount of idle time.

We can't figure out an obvious way to do this with xscreensaver. The
man page explains,

"Options  to  xscreensaver  are  stored  in  one  of  two  places: in
a .xscreensaver file in your  home  directory;  or  in  the  X 
resource database.  If the .xscreensaver file exists, it overrides any
settings in the resource database."

In other words, you can set this up system-wide, but users can
override it with their own settings. I can think of obfuscatory ways
to prevent that most of the time (break xscreensaver-demo), and
reactive ways to keep it from happening for long (startup scripts that
delete user settings). But we can't figure out the *right* way to do
it. Any advice?

FYI, I have seen references to xlock and xautolock, which sound like
non-daemon competitors to xscreensaver. Might they help?

Thanks,
Matt