There is, here's the code that shows the command line option: https://github.com/jackjack-jj/pywallet/blob/811c6bee054657783e7c2683bdfded5700241e17/pywallet.py#L3939-L3940
You can also refer to that link to check if you're using the official pywallet by jackjack.

Even jackjack himself has posted instructions on how to use the command here: https://bitcointalk.org/index.php?topic=34028.msg3378030#msg3378030