I read that molasses is called 'Raab' in India. Is that correct? I would think you should be able to get it at any health food store.
Or you can go to on-line health stores and order.
Natures Basket Stores
Global Health Supplies
GoIndiaOrganic.com
Sorry I don't have a source for kolkata, but I thought I would post this in case you can't find an answer.
If you find the pickling lime (calcium hydroxide) let us know what it is called in your country and where you found it and I will add it to the international list. Same with the molasses if you find a shop to purchase from.