You probably already have 1/2 of what you need, at least according to the NEC. Your branch circuit breaker can serve as the required disconnecting means and if it is not within sight of the ovens, you can install a padlock attachment on the breaker (get one from the same manufacturer as the breaker). Also, unit switches can qualify as the required disconnecting means.
See 422.31(B) and 422.34 (2002 NEC).
Few things are harder to put up with than the annoyance of a good example.