Well you need to separate your sphere mesh representation from the node representation anyway. As long as you know which face is across from the cube edges it is pretty easy to build the adjacent node list. Using just 4 neighbouring nodes eliminates the 7 neighbour problem at the corners too.
yes I understand now, it's going to be a pain getting the nodes from each adjacent face as rotation of the face as well as its adjacency to the "active face" will have to be calculated in order to return the correct edge. Would using just 4 neighbouring nodes make the algorithm much slower?