Anyone added a second 3.5mm aux port to an existing one?

atropine

My Z is great the way it is, but I just picked up a 2010 Toyota Sequoia for the family. It has the OEM JBL stereo system and factory Nav, with USB and 3.5mm aux input ports on the dash (not physically contained within the stereo/nav unit). I am going to have an aftermarket rear DVD system installed and I would like to wire the sound into the factory 3.5mm aux port, but do it behind the dash so it is clean and doesn't leave an external wire exposed. I would also like to retain the factory aux port so that if I want to plug any other device into the system I can. I would like to have remote switch mounted somewhere that lets me toggle between the DVD sound and the dash aux port. So essentially I want to splice into the factory aux input wiring behind the dash and add a second line. I realize I could just do this with a cheap $5 Y-splitter plugged into the existing port and then manually switch the input cable source, but that wouldn't be fitting in a $50k vehicle. Anyone know how to do what I am suggesting and where I could locate the necessary parts?