Since nobody is gonna see you PC inside, anyways, I suggest this...
Find one of those USB plates that fills up a slot on the back of your PC and attatches down to the motherboard on the inside. (It's a connection typically reserved for forward-mounted PC case USB ports, but they make plates so that your extra USB ports stick out the back.)
You could cut a small hole in your control panel (or underneath and just mount that one piece to it. You would have to cut off the ends so it wouldn't look like a plate, but i think it would work great and would look professional. (And if not professional, than certainly small enough to hide.)
Even if you were to try and use that piece you found, it would still require some sort of mounting plate. This is a nice all-in-one solution that is also easier to attatch to your pc.