American (military) living in Japan needing a double entry visa for China

Hi, I am an American living on a military base close to Nagasaki, Japan. I am planning a trip-- Shanghai- HK- Shenzen - HK over a 2 week period. I have a valid US passport (good for over 6 months), a passport photo, airline and hotel confirmations and the paperwork to fill out. Can I just take these documents - in person to the Chinese consulate in Nagasaki, pay the fee, and get a double entry visa for China? How long does it take? Do I need any other documents? Thank you so much for your help!