Start up a new season (any team you want) and make sure you have the following settings:
Trade Restrictions = NO
Trade Deadline = NO
CPU Roster Changes (something like that) = YES
The rest of the settings do not matter.
Now sim to the NEXT TO LAST game in the season (meaning you will have 1 game left when the sim ends).
Now, go to the GM Desk and check the League Leader statistics for the season. Take note of the top 15 scorers in the league.
Then trade your players for each of those 15 players (so you have the 15 top scorers in the league on your team).
Once you have done that, just sim the last game of the season and pop goes the cheevo!