USB Method: Make sure your usb drive is formatted from the 360 and has a profile created ON the USB with NBA 2K12 saves already on it. Best thing to do to avoid any problems is to create a new profile on the usb stick first (or if you already have a profile that was created on the usb, then that's fine too).
I know there are many other methods of doing this and if you already have a method that works for you then keep doing what your doing. I've tested this method and i know it definitely works. Just follow the directions carefully and you will not have any problems.
NOTE: Do not rename, edit, or alter the Roster file in any way or it will say "corrupted" when you load it in the game
1. Plug USB Drive into Xbox 360
2. Create new profile and select "Memory Card" (If you already have a profile that was created ON the usb already then that's fine, just skip this step)
3. Load up NBA 2K12 and get to the main menu. It will create the default save files. After that exit the game. (If you already have a profile on the USB and already played NBA 2K12 once, then skip this step)
4. Download Modio and extract it
http://www.mediafire.com/?vfdb3yihtc8o7je
5. Plug USB into pc and run Modio
6. Click the Big "M" in the top left corner and select "Explore My Device"
7. A new window pops up. Click "File" then click "Open/Close Device"
8. Now click the little plus sign to the left of "Content"
9. Now you should see all the profiles on the USB listed by name. Double click the one you just created or the one that already has the NBA 2K12 save files on it
10. Now you'll see "NBA 2K12" listed, so Double Click "NBA 2k12" and then double click "Game Saves"
11. Now you'll see all different 2K12 save files in the box to the right (Game Sliders, Settings, Roster, etc..)
12. Right Click in the space underneath the save files and select "Insert File" and browse to wherever you downloaded the rosters from this post (Alternatively, you can also just drag and drop the file)
13. Click "File" and then click "Open/Close Device"
14. Thats it. Plug into 360, load NBA 2K12 and test it out
15. You will most likely have to go into the game options and load the Roster file yourself.
You can also use various other programs like usb xtaf explorer... Guide is provided from the CosmoKramer420 thread [X360] NBA 2K12 Official and Custom Roster Downloads. Thank him for the guide. The mediafire link is for a offline install, which is the only way to get the roster working.
I tested it out and I gotta say I'm back in 2k11. Thank you for this great piece of work @MK. I'm Using it with your silder set and it works like a charm. Only have one note, by many of the recent trades you gotta adjust the sneaker colours to the native team colour. Which isn't that hard. Again thanks for this!