RHEL5 Mount USB readonly for security

Can anyone help with how to automount USB devices read-only for security?  I've hunted around and I can't find a clear answer and my various attempts have failed.  Here's where I'm at which isn't working.

I have RHEL5 and from what I can tell HALD manages the automounting.  HAL seems to have 2 primary directories:

/etc/hal/fdi

-and-

/usr/share/hal/fdi

The difference between the two is unclear to me.

Based on some examples, I created the following file:

--------------------
 



    
      true
    
  


--------------------

No matter what I call this file or where I put it, any USB device still mounts RW.  How do I fix this?  (Note, I'm looking for the generic solution for any USB device, so I'm not looking to hardcode something into /etc/fstab.)

Thanks.