http://forums.virtualbox.org/viewtopic.php?t=4960
Log in as root and type in terminal:
yum install gcc -y
yum install kernel sources -y
yum install kernel-devel -y
Restart the system.
Mount the VboxGuestAdditions.iso.
Move to the following directory:
cd /media/VBOXADDTIONS_2.2.4_47978
As root execute:
sh ./VBoxLinuxAddtions-x86.run
Restart the system again and good luck!
