For Xbox 360
1) find a friend that has the wanted dlc.
2) ask him to send you his account info. (pass and email)
3)recover his account.
4) go to http://www.xbox.com/en-US/support/sy...ensemigration/
5) sign in on his account.
6) hover you mouse over the support tab then click license transfer in the drop down menu.
7)follow the on screen step until you see finish.
8) on the xbox press the guide button. go to the tab furthest right and click account management.
9) click download history.
10) download the wanted dlc and your done.
I used to do this a lot and you can do as many accounts as you want on 1 console, you can only transfer the license on a profile once per year.
Also on your friends account they can only use the DLC / game when they are connected to Xbox live.