As Nigel said it will stick to the dots,
I haven't got a Focus either but the camera / sensor cluster on my mk4 Megane is even bigger, I have been playing around with it today and decided the best position was just lower than the dots as higher up it caught the edge of the sensor cluster in the picture, I would plug it in and use the wifi onto a bigger screen e.g. ipad and you can easily guage the best position then, prior to sticking it on,
I chose to put it on the passenger side as its off centre either side of the cluster and due do driving on the left in the UK I would prefer the slightly better coverage that side (I have the BT button to protect /save files when required)
Nigel - I too tried that location (on the underside of the cluster) picture wise it was good but being almost flat you couldn't see buttons or screen at all without leaning underneath,though the one in the picture looks raked like the windscreen so may work well if its not too flimsy