http://www.mongodb.org/downloads
http://docs.mongodb.org/manual/tutorial/install-mongodb-on-red-hat-centos-or-fedora-linux/
If you are running a 32-bit system, which isn’t recommended for production deployments, place the following configuration in /etc/yum.repos.d/10gen.repo file:
[10gen]name=10gen Repositorybaseurl=http://downloads-distro.mongodb.org/repo/redhat/os/i686gpgcheck=0enabled=1
yum install mongo-10gen mongo-10gen-server