I know I blogged about this previously and provided a link to download the web part but several people have wanted to know how to build it themselves so I spent my lunch time writing it up. I have also improved the demo by supporting the result offset in the Live search results to match the current SharePoint starting record number.
The first thing is to sign up an Application ID for and download the SDK from http://search.msn.com/developer/default.aspx?FORM=PDDD2
The next thing is to backup any custom XSL rendering and fields from your Search Summary web part because SharePoint Designer (SPD) may corrupt your custom XSL (as it did for me, trying to preserve white space).
Add a Web Service to the Data Source Library using SPD
Double click on the *Request parameter and fill in the fields shown below
Note: The Query and Offset parameters can have any default value but must be set at runtime.
Now you can view the values returned by the Web Service
And "Insert Selected Fields as" a Data View.
Now we need to tell the data view to get the current search string and starting record from the URL to use as parameters in the web service. From the Common Data View Tasks, select Parameters and add the source values (if you don't see Query and Offset in the parameter list then you forgot to tick the "Set at runtime" option when setting up the web service parameters).
It's as simple as that ;-)