Here is a pic of how it works with the fuse. (This pic is for a full size blade fuse instead on a mini like the G35 has).

<font color=blue>'04 G35S 5AT, Black Obsidian/Willow, Prem/Nav/Sat</font color=blue>

206725-fuse tap pic.jpg

 

Great! Using a multimeter, I have found the constant 12V source I will use at the fuse box, but I forgot to ask about the negative ground. Is it OK to use chasis ground or one of those "empty" fuse slots (using spare fuse), where I measured 12V between it and the positive source?
Thanks.

2004 G35 Coupe Diamond Graphite/Graphite 5AT
Premium, Nav., 18" Wheels, Z-Xtreme Hyper Grounding Cables,
K&N filter, Clear Corners, 350Z Aluminum Pedals

 

Chassis ground is the standard approach. Just make sure it's a tight, solid connection somewhere. Usually, there are screw connections all over the place.

<font color=blue>'04 G35S 5AT, Black Obsidian/Willow, Prem/Nav/Sat</font color=blue>

 

Sweet! Got this thing installed tonight. I ended up using the interior light fuse for the constant 12V, the bolt/metal frame right below the trunk release for ground, and the lighter for the switched 12V. I passed on the mute function since it's too much effort to get at the back of the stereo.
I placed the electronics box right above the gas pedal, the microphone left of the stereo, and the control panel left of the shifter. The only thing I haven't mounted is the speaker. I'm thinking about putting it on the front part of the seat (it would be either between the legs or behind the left foot), but am not sure if that'll work, so it's just sitting there in front of the driver's seat for now.
Big thanks to Noremac for all the pointers! Hopefully this will also help some future G owners who wants to install the HCB-30.

2004 G35 Coupe Diamond Graphite/Graphite 5AT
Premium, Nav., 18" Wheels, Z-Xtreme Hyper Grounding Cables,
K&N filter, Clear Corners, 350Z Aluminum Pedals

 

There is no good place for a speaker in this car, as I found out. I ended up placing it just beneath the glove box, aimed at the driver seat, and mostly hidden from view, using velcro.

Why didn't you put the microphone up around the mirror? It's easy to slip the wire behind all the trim leading to that point, and the mic will work much better at face-level.

Lastly, I'd like to see some pics if you have them!

<font color=blue>'04 G35S 5AT, Black Obsidian/Willow, Prem/Nav/Sat</font color=blue>

 

Picture of speaker from driver's view.

<font color=blue>'04 G35S 5AT, Black Obsidian/Willow, Prem/Nav/Sat</font color=blue>

207718-Speakerview.jpg

 

Picture of speaker underneath the glove box. (This is the Cellport system speaker).

<font color=blue>'04 G35S 5AT, Black Obsidian/Willow, Prem/Nav/Sat</font color=blue>

207719-speaker.jpg

 

Picture of microphone installed on the stem piece leading to the rear view mirror. This is also the mic that comes with the Cellport, but most others are very similar. It is attached with velcro, and the wires are almost completely hidden in the stem piece, then inside the headliner and pillar trims.

<font color=blue>'04 G35S 5AT, Black Obsidian/Willow, Prem/Nav/Sat</font color=blue>

207721-microphone.jpg

 

Well, I didn't really know how to route the mic under all the trim pieces to the mirror, and I actually didn't really want the mic there anyway. The place I put the mic actually works quite well. People at the other end hears me very clearly.
Here are some pictures:

This is the control panel.


This is where I put the mic.


This is where I have the speaker lying around. I might attach it to the seat right above where it sits right now, but I think I just might leave it lying on the ground. So far it seem to work well.


2004 G35 Coupe Diamond Graphite/Graphite 5AT
Premium, Nav., 18" Wheels, Z-Xtreme Hyper Grounding Cables,
K&N filter, Clear Corners, 350Z Aluminum Pedals