auto fetch of data on scroll

If someone is willing to give me a really great start on how to hook into the grid to extend it to auto fetch data on scroll, I need the capability and would share the experience. I'll be doing it immediately if my project timeframe allows the extra effort and it's not too big. So far it looks pretty hard to understand scrolling just by looking at the source code.

The idea is to make seamless fetching of data against a large dataset on the server, getting one window of data at a time. The user wouldn't know that it's happening except for a small delay when the fetch occurs. Let's say the server has 100,000 rows in the dataset, the window of data on the client that the grid uses could be specified at 200 rows, and the grid could be specified to show 20 rows. The user could drag the scroll thumb to the middle and the mechanism would fetch that data window of 200 rows from the server. As long as the user doesn't attempt to scroll outside the client window of 200, so server data access is done.