Get either
XPort360 or
XPlorer360. I use XPort360 myself. I actually use a flash drive these days but this used to be the norm for me. XPort seems to work a little better.
What you need to do is find your game ID folder on your hard drive. Actual game folders are located in partition1>your profile(s)>game ID folders. Look for the NCAA 12 game folder. I don't know the game ID for NCAA 12 right now. It's best to have a save already on your HDD so it will show up.
Once you find your NCAA 12 game ID click on that folder. Then drag & drop the new signed file into the right window pane of XPort360. It will inject the file into the game folder. After a few seconds you're done. Close the program out & load up the file from NCAA 12. Hope this helps you out. Thanks!