Getting the part with the Aux port out is the hardest part. Then you can remove a small circuit board. Buy a stereo female stereo jack at Radio Shack and put it in the AUX panel. I then bought a cable to connect the the audio input (VTR) on the AVN726e and cut and soldered the other end to the jack mentioned above. Now I can plug in an MP3 player and select VTR as the source. Works fine.
While your at it, buy a USB extension cable and install it into the dummy blank next to the AUX jack. You can then plug in a USB drive with music on it. You can see a picture of it here:
Have you had any problems entering addresses for the Navigation? Try to enter an address such as: highway 46, US 206, CR 517, RT 10 etc. You can't do it. You can't enter anything but named streets according to tech support. Eclipse has acknowledged the problem but no fix.
When it gets a little warmer I'm going to connect the factory reverse camera to the AVN. I'll post when I ever get it done. Good luck.