Nope won't be possible that easy Nearly but not completly.
Tiocfaidh ár lá
It would probably be better to install BackTrack then add the Ubuntu repo's you want. Just don't use the normal Ubuntu repo's for kernel upgrades.
then bot in to ubuntu:
sudo su -c 'echo deb or src [u r l]hxxp://whateveradressuneed[/u r l] >> /etc/apt/sources.list'
gpg --keyserver subkeys.pgp.net --recv "the gpg u copied from bt4 apt-key list"
gpg --fingerprint "the gpg u copied from bt4 apt-key list"
gpg --export "the gpg u copied from bt4 apt-key list" | sudo apt-key add -
im not using bt4, waiting for the stabel one, so i have no idea if this chit works out side hardy.
Use wget to add the public repository key to your sources with the command referenced in the title I wrote above... Sorry, I cannot post url's unless I make 15 more posts first.
Here are the repos (without the http: - You should know where they go - Hint = _ )
deb _//archive.offensive-security.com pwnsauce main microverse macroverse restricted universe multiverse
deb _//archive.offensive-security.com/repotest/ ./ # BackTrack Devel Repository
I agree with PureHate somwhow but I desagree on his desicion of leaving the instructions in the forum. People show some respect for the developers of BT, as has been said, the work is A LOT...and donations poor, and not NO CREDIT... i mean... take it down...