Installing packages for use under Virtual Box

Hi, am installing RHEL 6.1 under virtual box for testing, and have hit a snag.  VB requires several packages to be installed to access 'shared directories' under the host machine.  The following packages are not installed per 'yum list installed grep [package]

dkms
kernel-devel OR kernel-pae-devel
glibc-headers
glibc-devel
kernel-headers

I tried installing dkms using kernel-devel-2.6.32-131.0.15.el6.i686.rpm, but no joy.  There are a lot of RPM files on the CD image.  Can you direct me to the correct file?

Thanks