2010 A4 Avant S-line fitting charger

[chris_elevate]

I'm looking to fit a brodit phone holder that also charges the phone. How easy would it be to feed the thin brodit wire into the dash (nr the radio area) and the trace the cable to the fuse box and pic up a spare switched live slot in the fuse box and find an earth? The brodit has a fuse fitted so it's not necessary to have one on the box. Oh and where is the internal fuse box? I'm guessing somewhere to the right of the steering rack?

Thanks for your help and advice.