He'll have to redo the green card process. File I-130 to initiate the process, with a consulate in India selected for question 22.
PLS NOTE: There is no place on form I-130 where you can ask for consular processing and specify a consulate.
If the relative is already overseas, then consular processing is the default. No need to ask for it, and there's no place on the form to ask for it.
Only if the relative is already in the US and seeking Adjustment of Status, but potentially might not be eligible for AOS, should you specify a location for consular processing in item 22 of form I-130.
Hope this helps.