As you probably just saw, I just went ahead and got some information from Cyrus on how we currently do this from the Olson database, and shared it at <
http://trac.calendarserver.org/wiki/UpdatingTimezones>. I hope this is sufficient for your purposes. It could probably be less of a multi-step manual process, so feel free to file a trac ticket anyway.
As I understand it though, in addition to the tool in question dealing with the Olson format and not tzdata, we also need a bit more information from the Olson database than the zoneinfo database uses, so it really will need to go back to the source material. I don't think it can even be modified to derive the data from the tzdata package.