A change in crossdev default headers settings worked for me:
http://bugs.gentoo.org/show_bug.cgi?id=230343
Be sure to have mpfr and gmp up to date, they are required for building gcc.
EDIT: I got that working with gcc 4.1.2 and binutils 2.18.50.0.7 installed with emerge and explicitly set when calling crossdev.
Now I'm looking for an usb cable 