Why don't you simply open inittab with your favorite text editor?
UAH UAH UAH... YOU MAKE ME LAUGH!
Seriously, now. Here is the dirty way:
cp -p /etc/inittab /etc/inittab.bck
sed -i 's%ca::ctrlaltdel:/sbin/shutdown -t3 -r now%# Changed 8-5-08 -dfezz1 (disabling ctrl-alt-del at console)\nca:12345:ctrlaltdel:/bin/echo "CTRL-ALT-DEL is disabled"%' /etc/inittab
The -i option of sed edits the file in place (hence the backup copy). After the substitute 's' command of sed you can use any character as separator: when you have slashes in the pattern you can escape them using a backslash or chose another separator, as the percent sign in my example. Also you can insert a newline character in the replacement string to span the output on two consecutive lines. Just a dirty way, I know. I will think about a better one for the next couple of minutes!