You have to edit Pedpop.dat (\Rockstar Games\Bully Scholarship Edition\Config\dat\Pedpop.dat)
The default configuration only allow students, bullies and nerds to spawn in the boys dorm. If you want ivan (and the jocks) to spawn in the dorm just increase the red number to 1, 2 or anything else than 0:
Boys_Dorm
5, 0, 2, 0, 0, 0, 0, 2, 0, 0, 0, 0, 1,
1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0,
4, 0, 1, 0, 0, 0, 0, 2, 0, 0, 0, 0, 1,
1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0,
The first numbers (5, 1, 4, 1) are the total, so if you increase the jocks population, you should increase the total population too (or your game will crash).
This method is very old but still efective to this day.