To install VirtualBoxAdditions on Fedora 14, you need to install a few a few additional packages. In this example, I use a fresh install of Fedora 14.
Here are the packages that you will need.
sudo yum install perl dkms gcc kernel-devel kernel-headers
Now is not a bad time to update your kernel (though not required)
sudo yum update kernel
I reboot to the updated kernel. Then I mount the VirtualBox Additions volume.
cd /media/VBOXADDITIONS_3.2.10_66523 sudo ./VBoxLinuxAddtitions-x86.run
It should install without issue. You will need to reboot to enjoy the new additions.