Bear with me, hopefully I don't jumble my words.
jwin's method works, BUT you must do it yourself at the conclusion of the playoffs. If you are willing and able, you can add your own rookies to the game by editing the DBF at the conclusion of the playoffs.
What isn't possible is adding players to the DBF then distributing the file, which is then used to start a season ie. adding them to a current roster patch. This method worked with NBA Live 2000 and 2001, but not with NBA Live 2003.
So...
Add rookies yourself by editing your Franchise...YES
Add rookies to a roster patch which is used to start a new season...NO
Information subject to corrections and new discoveries.
