You'll notice that that handsfree device is made to fit into a standard drink holder. I'm not too sure that it would be the best spot in your car (I drive with my left hand on the steering wheel and the right on the gear selector usually and even an empty drink holder makes it a little uncomfortable.)
That cupholder attachement comes off by simply unscrewing it. I'm actually now looking at the driver'* side B pillar as a possible location for the handsfree speaker. POSSIBLE. Still playing around. I have no plans to put it in the folding drink holder. That Pro-fit device is a neat idea, but looks like it would interfere with the glovebox. It does give me a couple other ideas though.