I've never tried it with CentOS (or any server), but with other systems, I used xmodmap. This probably only works with xwindows running, but I'm not sure.
Using xev, you can find the keyboard codes for various keys. I believe 66 is the caps lock key.
Then, in a terminal, type these lines:
xmodmap -e 'keycode 66 = Control_L'
xmodmap -e 'clear Lock'
xmodmap -e 'add Control = Control_L'
Test it out to see if it works OK, then type:
xmodmap -pke >~/.Xmodmap
Now, any time you type xmodmap .Xmodmap, it will remap the keys. To keep from doing this on every reboot, add a line ~/.xinitrc, like so:
xmodmap .Xmodmap
There is an article on something similar here You can search for "xmodmap" to find more articles.