Install VirtualBox to Linux Mint 12

1. Add the below line in the /etc/apt/sources.list

deb http://download.virtualbox.org/virtualbox/debian oneiric contrib

2.Add the Oracle VBox public key

wget -q http://download.virtualbox.org/virtualbox/debian/oracle_vbox.asc -O- | sudo apt-key add -

3. Install the VirtualBox using apt-get script

sudo apt-get update

sudo apt-get install virtualbox-4.X