Re: Is it possible to do extra comm with usb-hid keyboard?

That means you must install libusb drivers on the target.
If you're going to do that, there is no need for a composite device descriptor, libusb can access mice and keyboards without any tricks.
The method I described doesn't require any drivers or libusb to be installed.
However, using libusb means it will pretty much work on any platform which is always a good thing