How to build multilib RPM package in X86-64

[helloworld1]

I am running Fedora 12 x86-64. I have a SRPM and want to build both x86-64 and i686 package. But the rpmbuild -ba can only build x86-64 package. --target=i686 is not working fine too, it try to find dependency in /usr/lib64. How can I build i686 package? Thanks!

[RahulSundaram]

Something like

# setarch i386 rpmbuild --target=i386 --rebuild bar.src.rpm

Better option is to use Mock

http://fedoraproject.org/wiki/Projects/Mock