I can't seem to run an installer with this extension. googling I find no one else with the same problem, which makes me think this is something which should be handled natively, only apparently it isn't. Can anyone shed some light on this? Thank you in advance!
It can't really be run alone, it's used to tell packaging applications how to pack the application into a real application.
To put it short, it can be used with the application Iceberg:
Do note that this is ancient code, and may not work (supposed to work from OS X 10.2 and up).