Applying for the Z Visa in the USA

Hi, I'm Brazilian and my husband is American. I'm currently being employed by a Chinese Organization and going through the whole paperwork process to get the Work Permit and the Invitation Letter. We are currently in Brazil, but will be on our way to the States soon. My employers in China don't think they will be able to e-mail me the Invitation Letter and Work Permit before I leave for America and in order to get the Z, I do have to present those docs. Do you think I could apply for it at one of the Chinese Embassies in the US?

My husband will be applying for a dependent type, and because he's American, I don't think that there would be any problem for him to be entering the process in America. But I only have a Brazilian Passport, I haven't started the USA naturalization process yet. We do have our Marriage Certificate though. My employer said they would be able to e-mail me the required documentation while I'm in America. I just need to find out if it would be possible to get one I'm there.
Thank you very much for your time!