I tried crossdev-20100108 with target x86_64-w64-mingw32 and got a patch error when portage tried to build mingw64-runtime-20091222. The patch mingw64-runtime-20091222-mm_shuffle_ps-x86.patch fails to find the target file. Looking in the ebuild I see that the patch is applied in ${S}, which would be ${WORKDIR}/${P}. However, only ${WORKDIR}/trunk exists. The patch applies cleanly when it is run in ${WORKDIR}.
Created attachment 216220 [details, diff] cd to correct directory for applying the patch
Created attachment 216222 [details, diff] cd to correct directory for applying the patch, now with correct old/new
thanks, fixed in the tree http://sources.gentoo.org/dev-util/mingw64-runtime/mingw64-runtime-20091222.ebuild?r1=1.2&r2=1.3