Basically you'd have to copy most of the values over manually. It would be a really, really long process. It would be quicker to simply update the rosters yourself if you don't want an update with changed ratings.
and what would you do about all the extra guys that Andrew adds to the rosters....the player list EA put out with the game as more holes than swiss cheese
Those would have to be added as well. It's possible, but it would be really easy to mess up the files and you'd probably be spending more time than you would updating the rosters in the normal fashion.