Prerequisite:
yum install yum-priorities
Make sure that yum-priorities is enabled by editing the /etc/yum/pluginconf.d/priorities.conf file, and ensuring that it contains the following lines:
[main]
enabled=1
Edit the .repo files in /etc/yum.repos.d/ and set up priorities by adding the line:
priority=N
to a repository entry, where N is an integer number from 1 to 99.
The recommended settings are:
[base], [addons], [updates], [extras] ... priority=1
[centosplus],[contrib] ... priority=2
Third Party Repos such as rpmforge ... priority=N (where N is > 10 and based on your preference)
Based on architecture: uname -i download the corresponding rpm into your downloads directory.
wget http://packages.sw.be/rpmforge-release/rpmforge-release-0.5.1-1.el5.rf.i386.rpm
rpm --import http://apt.sw.be/RPM-GPG-KEY.dag.txt rpm -K rpmforge-release-0.5.1-1.el5.rf.*.rpm
rpm -i rpmforge-release-0.5.1-1.el5.rf.*.rpm
yum check-update
Now you will be able to install dkms (You need sudo access to run these commands)
1) Devices > Install Guest Additions
2) Browse to the Guest Additions CD on the desktop, right click and open terminal. Run
sudo chmod +x VBoxLinuxAdditions-x86.run
3)yum install dkms
4) sudo yum install kernel-devel kernel-headers
sudo sh ./VBoxLinuxAdditions-x86.run
This will automatically switch VM to Seamless Mode and the resolution upgraded to 1024x768. You can now copy/paste from host to guest and vice-versa.
References:
How to Install Virtual Box Guest Additions for a Linux Guest
RPMForge
