I haven't used it directly, but I do make "sourdough" using beer yeast in a starter.
Mix a quarter cup AP flour and a quarter cup wheat flour with water (enough to get a wet dough... think sticky batter consistency). Add yeast and let it go for a couple of days. Then, keep this starter going by discarding most of the batter, and replenishing with the same amount of water/flour mixture. After a few generations, it's yeasty, funky, and makes a fantastic sourdough loaf. Purists aren't into this, as they want just wild yeast/bacteria, but it's much more reliable to kick start with yeast.