Added shock and tilt sensors to the factory alarm last week. I wired it all near the BCM in the passenger side footwell. Those BCM wires were a pain to splice into. I took some pics which I'll post later when I get a chance.
The only thing I would have done different is probably use shorter wires for everything. I originally planned to put the sensors in the center console but found I could easily fit them near the BCM. I was too lazy to redo the wires so I just taped and secured the long wires.
Thanks to this thread for making the wiring easy:
http://www.the370z.com/nissan-370z-g...ory-alarm.html