Need help finding ignition wire

Hey guys im helping a friend install an amp in his car this weekend but hes using a stock deck so i need to find a ignition wire to turn it on. From what i know theres one in the fuse box but im not sure how to access it and stuff. Can anyone give me tips or let me know how to access the wire, or if theres an alternative route to getting a remote turn-on for the amp. Oh and its a 2002 civic so pretty much same honda stuff.

pull the stock radio out, there should be a diagram on the back (there was on my 91 accord, and 93 civic, my teg came with a cd player all ready installed). and look for it. that would be my guess on how to get to it easy (tho tearing it out might be hard on new civics). my civic (92-95) are easy as **** to get out. so this might not be a big option for you

I can’t remember exactly right now, but I believe it is about a 10 awg wire that is either black with yellow stripe or black with white stripe. One of those is the starter wire, and one is the ignition. Meter the wire, and the one that get’s you voltage when the key is in the “on” position is the one you want.

Good luck!