Good news, I got the library installed and dfu-programmer to run.
I can't get it to do anything useful, though. I can't figure out how I'm supposed to designate the "target" device. I read the --help instructions, then I tried digging into the Windows device manager to locate the USB bus and address. Then I tried:
> dfu-programmer atmega32u4:00000000,00000001 read
Unsupported target 'atmega32u4:0,1'.
And then a long list of the controllers it supports.