You will need 8.5.3 and the latest release of the extension library (when available) . There is a simple demo of the functionality here. This functionality is probably the most requested or discussed feature that Xpages could really benefit from. I think that this will be a very useful lever for companies looking for integration options between Domino apps and line of business apps. The demo shows readonly and cached rowset Read/Write capabilities. It also shows the @ Functions which make these operations much easier for developers getting started with Xpages and relational data. This new development makes relational data (where appropriate jdbc drivers are available) almost as easy to work with as nsf data.
There is also a deck with details here —– http://www.openntf.org/Projects/pmt.nsf/02E46D1F3808B0F4862578D40057CB5C/%24file/XPages%20Goes%20Relational.odp