Documents required to get marriage registered

I want to marry my girlfriend.She and I are a relationship more than 6 years We have a serious problem in our family that my girlfriends parents and ours not allowing to marry us. so we think that want to get married secretly with our best friends. the problem is that my girlfriend and i are a permanent resident of kanyakumari district but she is working in chennai more than one year . we want to get register marriage in chennai with special marriage act 1954 but this law requires residence proof of a particular area . what should i do to get married in chennai.