Its not that easy as you think and it also take more time than you think..
I did it as soon as I had some time available.
http://rapidshare.com/files/289168613/winceimg4.rar
Now, every file/rom I made I checked myself on my AVIC S2 except this one, my AVIC S2 is dead, sent it to repair, so I cant check this rom, and guarantee it works. So if it doesn't please let me know.
Of course you can go to ppath.txt and change direction, takes 1 minutes, but after you turn it off you will have to do it again, with the ROM it won't loose those setting. I explained everything in the first page