What are the laws on same marriage in Mexico City?

My boyfriend and I are intending to get married. He is unable to come to the United States. It's proving a bit difficult to get a FM3 and I only have a FMT. I don't make enough money for the income requirements for a FM3. I understand the laws concerning foreigners marrying Mexican citizens, and that the law recognizes same unions in the DF and Coahuila. but how does that apply to same couples? If marriage/union is not an option, how can I become a resident or something of that nature?