I did this mod tonight and here are my thoughts.
1. Use a flat blade screw driver to take the flap off the side panel.
2. Getting that round pin out wasn't easy, had to work it loose and carefully pull at the panel the way described, make sure you remove the front floor mat.
3. I ordered the monoprice adaptor as mentioned earlier but it would not fit so I had to shave it down, then I was able to get into the connector. I'm thinking about using a Standard USB mini 5pin male to Male USB cable and getting one of these:
This way it will fit better & we can try to connect a USB Memory stick into the adapter as well as an I-pod, will let you know if it works better!