You'd have to take the derivative with respect to time, I'd think, because the ejection rate might decrease with pressure.

Instantaneously, with a 1mmHg/min leak I think you'd lose roughly 1.5kg or a little over a cubic meter's worth in the first minute, given the 915.6 m^3 pressurized volume and a mass of ~1.3kg/m^3 for air at sea level (760mmHg, which is close enough). How long it takes to get down to an unsurvivable ~250mmHg (assuming an Earth-air-like breathing gas aboard ISS, which seems reasonable) takes more trouble to figure out than I care to go to on a Friday night, but the lowest possible bound (assuming a constant ejection rate) would be somewhere around 500 minutes, or between eight and a bit to nine-ish hours.

Honestly I'm more curious what area a breach would have to have to produce that kind of leak rate.

edit: Actually, given the effectively infinite volume at effective vacuum outside the hull, you wouldn't see the same "counterpressure" effect you would in atmosphere, that causes pressure equalization to slow down as it approaches equality - there's no equalization that can happen here. That said, you'd still lose less mass per unit time over time, as the internal pressure and thus the mass per unit volume drops.