The stereo that this mod applies to is the Nissan 2000-2004 XE's stock deck.  Later years won't work and the SE package with the in-deck CD changer is a no go as well.  Casing point, you need to make sure you radio has the round 8-pin port in the back.

To explain how this is all going to go down in a more scientific manner, the stereo is connected to the 8-pin din plug, to the RCA Y-split, to the RCA output of your choice- or as you'll see, my nifty rigged concoction.

The first real step was the solder work on the purchased plug.  While it's not an easy task steadying your hand on minute weld work, there's really nothing to be afraid of.  The part your playing with is dirt cheap, and if you dip the attaching wire ends in flux they almost solder themselves.

The Y splitter is needed for the female RCA ends only.  You need to clip the phono end off the other end and strip the wires down for the soldering.

Using the service manual diagram, wire up the 2 positive and 2 negative speaker wires to their assigned posts (the center core wire is positive).  You will also need a length of wire to use as the power wire that will tell the stereo that Aux-mode is initialized.  Solder it to pin 1 and later on we'll connect the free end to a Ignition-On power source.

However ugly your solder work came out, you should now have your homebrew Plug-n-Play wiring harness.  Once we add a switch into the system, you will be able to play just about anything through your stock head unit.