Just did this on my '07 Spec.B. I have been wanting to for a long time and finally got around to it.
Maybe I'll have to investigate the signal on the red/grn wire to see if I can use it as an input. One thing my G35 used to do was I could roll down all the windows with the key fob by holding the unlock button. I could use an auto up/down module hooked to all the windows. Not sure, will have to look into it.
Thanks for the writeup.