I did quite some research - USB cards, data access card - which were quite expensive for the 1 week access that I needed. Finally ended up trying Airtel GPRS. The speed is dial up - as advertised. My site loads up fast and I am able to SSH. That is all I will need.
You need a data cable for your phone - so you can use your phone as a modem. Then send the message "MO" to 6123 - this is a week plan for Rs 140 - unlimited usage. And when you want to stop the service send the message "MO CNCL" to 222. Simple isn't it?
Also with the frequent power cuts I am facing - probably I will go for the 1 month plan - 100MB for 350Rs or so.
Thanks AR Rahman for the tune and Airtel for your awesome service.