theres a pinout that i used somewhere around here, (check the hybrid posts, or i can PM you it), then you need the famicom connector, i could send you the link to the one i used in sheeps mod, after that its just soldering pin to pin, by far the hardest part is mounting the fami slot!
im sure if you googled around you could find a pretty decent guide...
(if you ever wanted me to guide you through, id be more than happy to!)