After hours of research and trying to figure out how this stuff works, i've come up empty handed. Say, hypothetically speaking, i'd plug any random USB device into my laptop (yes, drivers are present). For the sake of discussion, let's say it's (ofcourse, usb driven) a dance dance revolution pad. What i'm trying to accomplish is to enable this device to serve as an input for my processing sketch. I figured that it should be possible to 'sniff' any communication from the pad to my computer and use that input to my advantage. Now with similar questions I've seen around here, I assumed this would be done using the Serial library, but i can't seem to get Processing to recognize any usb device attached to my computer. I've also seen some emulators lying around, but how do these things exactly work? Do they 'convert' an entire port, rendering it useless for standard USB use, or does this only apply to the device currently attached to that port? And if so, how do these relate to Processing?

In short:

For any USB device, is it possible to get the input from that device (no talkback) to use in my Processing sketches?

Thanks in advance - i appreciate any answers that might point me in the right direction!