The web page documentation at http://gcc.gnu.org/contribute.html doesn't really have the specifics of getting a copyright assignment done in the simple case of an individual contributing on his free time. I've set up a wiki page that we can refer people to, at http://gcc.gnu.org/wiki/CopyrightAssignment. Feel free to improve it or correct it.
FX -- FX Coudert http://www.homepages.ucl.ac.uk/~uccafco/
