I don't know about re-loading the firmware, but if you need to re-set the passwords, you can use the clearparam command as described in the opening post.
telnet into the camera, then type
This will do a 'factory reset' for all of the camera parameters - it will clear any user accounts that you may have created, and it will restore the camera default settings (passwords, ip addresses, overlays, etc).
When I ran this the process seemed to hang (as it has changed the camera ip address, and so the telnet session was mangled). But after waiting for the camera to re-appear as 192.168.1.108 I was able to access the GUI using admin and the default admin password.
Unfortunately, since I changed the Admin account password to a password I cannot recall, I can't enter the SSH/Telnet area to run the /sbin/clearparam command...