You're looking for the LotFullOfSims hack, but that is currently not available anymore where I got it:
http://www.modthesims2.com/showthread.php?t=212448.
I have the hack, but I don't know if it's okay to give it to other people. Maybe a mod can tell me if I may? Jordi doesn't seem to mind, according to his posting. But I guess there's a reason it is down. However, in my game it works beautifully with Seasons. Didn't try it with BV.
