The following information may be of some use to you:
such marriages are solemnised and registered under the Special Marriage Act.
First your friend will have to stay in the place she intends to marry for a month before filing a notice for intention of marriage before the local Marriage Registrar. For this notice, she has to appear with her would-be groom to the Registrar together.
All documents of identification, residence, passport, visa papers and two passport size photos of both will have to be added when filing for a notice of intention to marry.
Within three months after that, the Registrar will call them to solemnise the marriage with three witnesses. Once this is done, the marriage is recognised to be legal and the marriage certificate will be issued within a few weeks.
She will have to show proof of residence in the locality that can be done through address on passport or an affidavit from the local police station. In addition, evidence of eligibility of marriage will have to be shown. Either a single status affidavit or a divorce decree for a divorcee is required to be furnished.
For further issues, you can contact the local registrar office in Delhi.