TomTom external microphone

Just a quick question guys.

Assuming I am going to mount my tomtom (510, the old model) in the centre of my windscreen (horizontally), and that the mount is NOT going to be in the windscreen at all times, what is the best and neatest way to have the external microphone in the car at all times?

I did have it clipped on to the sun visor, then poked it behind a rubber-type trim finisher down the windscreen pilllars, and then down the side of the dashboard just as the cable reached the bottom of the windscreen, but then I have no idea how to hide the cable from the one side (right hand side) of the windscreen to the centre... I don't particularly want:

a) People to know I use electronic equipment in the car, giving them reason to smash the window and try to nick something

People to see dangling cables everywhere

I'm not set on having the microphone fixed to the sun visor, it just seemed the most logical place at the time... if anyone has fitted one successfully (and discretely) elsewhere, please help!

I did consider drilling a tomtom microphone shaped hole in one of the blanking plugs alongside the heater and ASR buttons, but then there's the whole issue of where does the wire come out from to plug in to the tomtom mount?