I have purchased the Motorola HF850 bluetooth car kit for my megane. I currently use an excellent visorblade but would prefer something more hidden and that works automatically when I get into the car - oh and they were only £10 on amazon last night

I need to get a power supply, earth and ignition source, so obviously the radio input is the obvious for this. However, before I start cutting the ISO cables for a supply, does anybody know of an ISO plug which is specifically made to enable you to tap off these connections (and mute if the tunerlist supports)?
My plan would then be, depending on cable lengths, to put the microphone by the sunvisor through putting it up by the pillar, put the control box maybe around the back of the glovebox, the control panel next to the controls for the headlight height/interior brightness (or infront of the gearstick) and the speaker in one of the footwells, hidden away.
I just wondered if anybody had any thoughts?
Thanks
Paul