Couple of thoughts - You could trace it (backwards, of course) on freezer paper, taped together to make it wide enough. You can tape it to a window and trace it that way, or if your dining table has a leaf, take the leaf out, put a piece of glass or plexiglass in its place and a lamp underneath the table, and viola you have a light table.
Another thing you can do is take it to Kinko's, I can't remember if they have something that will scan that big, but they are always very helpful and come up with creative solutions.