This is very easy , all you need is Cheat Engine.. or other hacking tools...
Open nba2k12 process on Cheat Engine and enter address manually, type in 00EF4648 as an address . Type is 4 bytes.
Here are some values on the default roster , values changes as roster changes...
Paul Pierce = 76
Kirk Hinrich = 116
Blake Griffin = 91
Dwayne Wade = 131
Chris Paul (Hornets) = 145
Carmelo Anthony = 188
Kevin Durant = 359
Monta Ellis = 400
The first value (1) starts on the first team alphabetically and the is that 76ers ..
The last value will be on the last team alphabetically and that is the Wizards..
There are 30 teams and approximately 12 players on each team so 30x12=360..
So I guess 360 is the last value... Just give it a try...
Just post message if the is a problem...
If the is a problem, I'll upload the trainer where I got that address....