To those who don't already have the game, you can in fact customize an entire squad of characters for use in multiplay. You do it all beforehand so that the other players aren't sitting around waiting for you to make your characters - you make them on your own time, choosing their race, hair color, equipment, level, everything. As you go the computer keeps a running 'point' total of the character for balance. Then in multiplay the host sets a point limit (so if you build a mega-character worth 40000 points, you won't be able to use him in a 10000 point game. And in a 40000 point game you'd be able to use him alone with no backup).
Hope this makes everything clear.
Zombra