I was toying around with my PowerMate USB on the Mac.
I noticed that in the PowerMate application, you can set triggers for mouse wheel scrolling. But some applications coughMAMEcough don't pick it up.
Investigating I found that it provides its spinner as a uncommon HID type. So applications ignore it, not knowing how to handle that.
The click is presented as a normal button though. So no big deal there.
brew install libusb
brew install hidapi
gcc -o hid_browser hid_browser.c -I/usr/local//Cellar/hidapi/0.8.0-rc1/include/hidapi/ -lhidapi
./hid_browser
Hershwild:~ jstillwell$ ./hid_browser
Manufacturer String: Griffin Technology, Inc.
Product String: Griffin PowerMate
Serial Number String:
Feature Report
00 00 00 f2 01 04
Turns out that you can get usb-utils for the mac (there is a port), and the lsusb command works great to dump the hid descriptors.