This concept was originally made by iHc James than superman and smile ported it to mw3 and FanGirl leaked it and i thats how i got it than edited it and put it as a option in the pause menu. Its a very smart concept and is something only iHc James would come up with, cause he is awesome But really, he took it from §link, as §link orginally created this for WaW.

You need to be able to mod, other than that you just download the file and replace the code_post_gfx_mp.ff in trucha signer

Public:
1.Go to the Options/Mods and select lobby(You should notice the game get faster)
2.Start searching for the gametype you want to host the xp lobby in
3.Back out before it finds a match and go to a private match
4.Change the map and change the gamemode to the same gamtype you where find a match for.
5.Start the game and it should end than go into a public and when your host it will be a lobby

Private:
1.Go to the Options/Mods and select lobby(You should notice the game get faster)
2.Start searching for the gametype demolition or sabatoge
3.Back out before it finds a match and go to a private match
4.Change the map and change the gamemode to either demolition or sabatoge.
5.Start the game and it should end than go into overtime and there is your xp lobby in a private(Xp sticks!)