Infinity m35 --2006-Homelink install

[toju]

I wish to install a Homelink interior rear vision mirror in my vehicle.
The new mirror fits ok on the windshield wedge attachment.However problem is that original mirror contains what appears to be a receiver for the intelligent key operation i. e. when the cable to the rear is unplugged nothing works.To operate the car you have to insert the key unit into the dash slot.But then you cannot lock the car as it has to be removed to lock from the outside.
Can the old mirror be opened[how ?]the circuit board and plug etc removed and placed in the map light cavity ?
All that needs to be done then is to obtain a 12 volt feed from the under dash fuse block.Leading the 3 wires around the head lining.
I am loath to do much here as I can see disaster looming if I am not careful.
Tony.
Ps.car is actually a Nissan Fuga--rt hand drive version of Infinity.