Rep Power: 0

In my 2003 Civic LX sedan:
I want to use the factory deck to power an outboard amp (I'm replacing all the speakers).
I plan on using a step-down adapter (speaker level to RCA line level adapter) which I'll attach at the factory rear speaker wiring near the amp I'll mount in the trunk.
Trouble is, I need a remote trigger out of the factory deck to tell the amp when to turn on/off.

From the basic research I've done it doesnt appear that the factory deck has an amp trigger wire. Can someone confirm this or offer a solution?

I don't want to replace the factory deck at this time (I'm cash poor). I have Alpine/ADS gear that I pulled out of my 93 Accord so right now I have the amp and speakers and no money out of pocket.

2003 Honda Civic Car Stereo Radio Wiring Diagram
Car Radio Constant 12v+ Wire: Blue/White
Car Radio Switched 12v+ Wire: Yellow/Red
Car Radio Ground Wire: Black
Car Radio Illumination Wire: Red/Black
Car Stereo Dimmer Wire: N/A
Car Stereo Antenna Trigger: N/A
Car Stereo Amp Trigger Wire: N/A
Car Stereo Amplifier Location: N/A
Front Speakers Size: N/A
Front Speakers Location: N/A
Left Front Speaker Positive Wire (+): Blue/Green
Left Front Speaker Negative Wire (-): Gray/Black
Right Front Speaker Positive Wire (+): Red/Green
Right Front Speaker Negative Wire (-): Brown/Black
Rear Speakers Size: N/A
Rear Speakers Location: N/A
Left Rear Speaker Positive Wire (+): Blue/Yellow
Left Rear Speaker Negative Wire (-): Gray/White
Right Rear Speaker Positive Wire (+): Red/Yellow
Right Rear Speaker Negative Wire (-): Brown/White

 
Rep Power: 0

theres two, well three things that can be done here. One is to use the Car Radio Switched 12v+ Wire: Yellow/Red. Two is figure out what wire is the Acessory On in your Ignition wires. Three is to run a wire from your battery with a fuse and toggle switch in the line right to your "remote on" on the amp its self.

 
Rep Power: 0

theres two, well three things that can be done here. One is to use the Car Radio Switched 12v+ Wire: Yellow/Red. Two is figure out what wire is the Acessory On in your Ignition wires. Three is to run a wire from your battery with a fuse and toggle switch in the line right to your "remote on" on the amp its self.

 
Rep Power: 264

Yeah accessory @ the deck or accessory @ the ignition harness (white/red).