Is it possible to pass a querystring paramater to a BCS List to help generate the query?
I know this is an old question, but thought maybe this would help others searching on the same issue. I followed this article step-by-step and was able to pass a querystring parameter to a business data list web part to filter the results: http://prashanthkn.blogspot.com/2010/07/displaying-business-data-list-web-part.html
Basically you just add a business data list web part (already configured to accept parameters when you created your external content type), add a query string filter web part, and then connect them.