I used an existing rubber plugged hole on the firewall by the back of the motor on the PS. I believe it is something for the hvac. I did have to poke a hole in the plug, there isnt one already. then under the trim on the PS to the amp under the back seat. I ran the RCA's and speakerwires under the trim on the DS.

If you still dont have it done I can stop by and let you see how I did it.