Freeradius 2.1.1 and SQLite database

Has anyone done any work with FreeRadius 2.1.1 or higher and SQLite as the backend db. Working on a single router solution with OpenWRT with FreeRadius running PEAP and EAP-TLS auth. Would love to have it working with sqlite as that is the smallest DB footprint of all the supported databases for Free Radius. Has anyone done work with the sqlite db and give me some pointers on the database setup for sqlite, looks like I need to create a file called "sqlite_radius_client_database" but not sure what the structure should be... And google isn't helping much either. Any assistance would be great. Many thanks Peter