Refugee travel document, living in USA with green card

Joe, you need to go to the PRC embassy or consulate in your district and see if you can apply from there. If not, you need to contact directly with HK Immigration Department and see if you can submit the application to the office. The documents may include your travel document copy, application form, an invitation letter from your business partner in HK (if any), round-trip tickets and hotel bookings, and a financial statement.