Like Fred, I do some of the basic transfers edits myself, but the overall all encompassing changes, I download exstensive patches that are player made, from here usually:
http://www.pesgaming.com/forumdisplay.php?f=330
They take a while, and its tricky if they fit your region/code of the game, but generally well worth the wait. Good ones do all the kits, all transfers, faces, all players that are missing, or even adding whole leagues (bundesliga, brasilian league etc).
But the fucking game isnt out in europe yet (i'm still playing the demo, needless to say, when game comes out, I will never touch tottenham, bayern or Inter even once lol), next friday, I have NO idea why the whole of fucking asia and North america got it like 2 frigging weeks before europe.