I think the easiest way is to access those files from a terminal using
sudo to elevate your privileges. For example,
sudo vi /etc/cups/cupsd.conf should open the file in vi.
See
http://linux.die.net/man/8/sudo for information on using sudo.
[looks like fordeck pulled the trigger quicker and with a good question. I guess I assumed that the OP was not running as root. Shame on me.]