BPEL runs on the SOA server . So you can't process the information on the client machine using BPEL .
I think you can do it with java . Get the content as a binary data in java using the api's provided by the device manufacturer and then invoke the web service likely the BPEL which takes the binarydata as input and you can process it from there
SOA suite is for processing data, business rules and hooking into other applications / systems to keep the information moving in real-time (ideally).
You could do this many ways.
I would look into using something like python, setup a rest webservice that executes a local command to mount the usb device and process the data. This can of course be done in java or a host of other languages... You need to specify what you're trying to do w/ the device, is there an api ?
Please lend some more info! Sounds mysterious and interesting!?