VirtualBox on Backtrack 5

Following are listed below to install virtual box 

root@bt # prepare-kernel-sources
root@bt # cd /usr/src/linux
root@bt # cp -rf include/generated/* include/linux/

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