This is not possible (to download historical data from Google Finance). I saw following statements on Amibroker site, while searching for the same issue.
"Google Finance page does NOT allow downloading historical data for non-US (international) symbols and some indices."
Really need reliable data feed for NSE Cash. Even though I am using bhavcopy for EOD database, its very tedious process to download Intraday data from NEST for so many scrips. I would like to have both EOD and Intraday data for CASH in the same database. Please suggest.