[B-R-Z]

I would place the LC6i somewhere behind the headunit and buy the appropriate Metra plugs (70-1761 & 71-1761) to intercept the speaker wires from the factory plug (to avoid cutting any of the factory wiring). This would be an easy way to get all 4 channels. I'm not sure if it'll fit behind/under the radio but you can definitely find somewhere in the vicinity. You can then run RCA's to the trunk. You can use the remote amp turn on wire that is used for the factory amp to turn on your aftermarket amp and LC6i.

This way you can put all high level inputs into the LC6i in one place. If you mount in the trunk you can only get the door speaker wires from the plug that goes into the factory amp.