First, install 'nasm' via macports.
Then, in a clean source dir, do this:
autoreconf -fiv
./configure --host x86_64-apple-darwin NASM=/opt/local/bin/nasm
make
NASM 2.07 or later is required for a 64-bit build on OS X. This can be obtained from MacPorts (http://www.macports.org/).