I have a simple wrapper around koji that makes possible to call koji for secondary archs with "$arch-koji" instead of "koji -c ~/.koji/$arch-config". Please consider including it in fedora-packager.
attachment secondary-koji
http://git.fedorahosted.org/git/fedora-packager/?p=fedora-packager.git;a=commit;h=c4e8a7e2c37b1b27e9ca0539e1a826eefa5b0d69
added to git. will be in the next release
thanks