Installing VirtualBox on Backtrack 5 R1,R2 or R3

If you have backtrack installed on HDD or dualboot you can install virtualbox into Backtrack.. The commands are listed below:
Follow My Steps:
Step 1.
Open Your Terminal
and type the exact commands (text in red) 

root@bt # prepare-kernel-sources

root@bt # cd /usr/src/linux

root@bt # cp -rf include/generated/* include/linux/

Step 2.
Open Up A New Terminal
After this is done, edit /etc/apt/sources.list as shown below and download virtualbox

root@bt # echo deb http://download.virtualbox.org/virtualbox/debian lucid contrib non-free >> /etc/apt/sources.list

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

root@bt # apt-get update

root@bt # apt-cache search virtualbox

root@bt # apt-get install virtualbox-4.0

Open Your Virtual Box By Navigating 

Applications > System Tools > Oracle VM VirtualBox