If you go to
www.ps2rosters.com, they have IAA rosters for ps2 and Xbox. You cannot replace every team with a IAA team because there are only around 70-75 IAA teams in the game. So, at best you can replace 87 teams(all IAA and you can create 12 more). You should find the best fit in terms of the number of teams in each conference and swap accordingly. You should replace all the BCS teams because otherwise they'll always be in the main bowls and I'm guessing you want as little impact in your results from IA teams. I think it's safe to leave the Sun Belt alone since it only gets 1 bowl bid. Other conferences that are low are the MAC and WAC although they get more bids than the Sun Belt. The best way to do it would probably be to replace all BCS teams, including Notre Dame in the Independents(that's 64 teams so you can replace 11 to 23 more depending on how many schools you created) and then replace the best teams from the other conferences with the teams you have left . You're still going to see some IA teams in your top 25s(Even the bad IA teams are rated better than most IAA teams) most likely but not having any in the BCS conferences should keep them from taking the most important bowl bids, except for possibly the two at large BCS bids. I hope these suggestions help. Enjoy!