I looked at the code, and it is something of a mess. I'll do my very best to clean it up during the weekend. In the meantime, check out the HID Utilities sample code from Apple - that's where I learned it all. Look at the examples, and you'll be up and running with HID in no-time.

Anyways, the code is up at http://www.rusted.se/hidstuff.zip

I know there are bugs in it, it doesn't work perfectly with all gamepads (which is a bit odd) but at least it's a starting point. There's a lot of hardcoded stuff, and it is not compileable. (Because of omitted source)

The source includes the following:
InputController.cpp/h - the classes for handling an input controller. You create a pointer of type BaseInputController (which is a singleton, by the way) and set it to point to an object of the type you want (GetKeys, Events, HID or ISp) - check out the header.
HIDDevice.cpp/h is just the stuff that encapsulates a HID device, of course.
HIDDialog.cpp/h is a configuration dialog in Carbon. It is written on top of the stuff in BaseDialog.cpp/h, which is a quite nifty way of doing Carbon dialogs, by the way. I've gotta run, but check it out! And do ask questions.