Need some Vent Help!

I'm growing 'dro in a 6 x 5 walk-in closet with 2 doors, but don't have any additional ventilation. I'm on 12/12 for 5 days now, and I need some help with ventilation during the dark 12. I'm already rollin' with a Honeywell HEPA filter and a 13-inch oscillating fan (which does a pretty awesome job of circulating the air) as well as a dehumidifier. Just need a way to get the air out. They exhaust unit for my central air is through the wall opposite the garden. I'm thinking of building this http://www.gardenscure.com/420/secur...on-filter.html, but I think I need a fan blowing in that mini-unit. Any suggestions or mods you guys can think of? Thanks

The LeBrons:stoned: