The prerequisite for it is being in the warshaper class (see the Complete Warrior WOTC sourcebook) and being at least 3rd level in the warshaper class... you can grow wings as a feat letting you fly at 30 feet with "average" maneuverability, see "flight " at
Purchasing this feat a 2nd time increases your fly speed to 60 feet and your maneuverability to "average" .. you cannot purchase this feat a third time.