What I do when I need to shoot a scene like that is make a set on a residential lot and then I use the summoner that comes with the insimenator to summon a bunch of people on to the lot, then I use the selector (or boolprop) to make them selectable and I direct them to do what I want to do.
Hmm.....this might work. I think I may actually use the zoning cheat to do it. I already have the lot built but it is currently a community lot. I'll change the zoning to residential then have the owner use the summoner. Thanks for the idea Naima!