However, in addition to diet, I would *definitely* recommend supplementing stone softening and stone breaking herbs as well. Malic acid (from apples), Gold Coin Grass, Chinese Bitters, and Chanca Peidra (also known as "stone breaker") are the ones that come first to mind and seem to have very good track records.
More details on liver function and cleansing, Gold Coin Grass (GCG), and Chinese Bitters can be found at Julia Chang's site, Sensible Health.
Also, Tim O'Shea has an *excellent* site to read concerning overall health called The Doctor Within. He focuses on the importance of clean bowels and clean blood for good health. The site is a "must read" *especially* the chapter "Journey to the Center Of Your Colon."