RH should have set it up for you, but if ain't happen here comes teh rescue crew, here is my section for input device from /etc/X11/XF86Config-4 file
Code:
Section "InputDevice"
Identifier "Mouse0"
Driver "mouse"
Option "Protocol" "IMPS/2"
Option "Device" "/dev/input/mice"
Option "ZAxisMapping" "4 5"
Option "Emulate3Buttons" "no"
EndSection
Option "ZAxisMapping" "4 5" is what you need