Start particle system with negative time?

I’m trying to start a particle system as if it had started in the past. For example, in the test project that comes with cocos there is a snow and rain particle test, and when you start the snow particle system you can see the beginning of the effect, where the snow starts. I’d like to create the particle system and instead of seeing the first few particles fall I would like it to look as though it has been running already, and have particles mid-air already at creation. Is there a way to do this? I tried calling the update() function with a time but that didn’t work.

bump. Anyone? This seems like it could be useful if it’s not currently possible.

As http://stackoverflow.com/questions/6623611/cocos2d-starting-particles-from-a-specific-time-in-the-future said,
you need to call update several times to generate particles. For example:

    CCParticleSystemQuad *particle = CCParticleSystemQuad::create("res/Particles/Stars1.plist");
    for (int i = 0; i < 10; ++i) {
        particle->update(.1);
    }