I am working on a project involving installing subversion and python on RHEL 4 server. There is no stock package manager there, so I needed to install one. This are the steps required, based on http://www.eth0.us/yum-rhel article.

mkdir /usr/local/src/yum 

cd /usr/local/src/yum


wget http://mirror.centos.org/centos-4/4/apt/i386/RPMS.os/python-urlgrabber-2.9.8-2.noarch.rpm 
wget http://mirror.centos.org/centos-4/4/apt/i386/RPMS.os/python-sqlite-1.1.7-1.2.1.i386.rpm
wget http://mirror.centos.org/centos-4/4/apt/i386/RPMS.os/python-elementtree-1.2.6-5.el4.centos.i386.rpm
wget ftp://ftp.isu.edu.tw/pub/Linux/CentOS/4.8/os/ia64/CentOS/RPMS/centos-yumconf-4-4.5.noarch.rpm
wget http://mirror.centos.org/centos-4/4/apt/i386/RPMS.os/yum-2.4.3-4.el4.centos.noarch.rpm
wget http://mirror.centos.org/centos-4/4/apt/i386/RPMS.os/sqlite-3.3.6-2.i386.rpm
wget http://mirror.centos.org/centos-4/4/apt/i386/RPMS.os/yum-metadata-parser-1.0-8.el4.centos.i386.rpm

rpm -Uvh *rpm

Afterwards you need to edit /etc/yum.repos.d/CentOS-Base.repo, uncomment baseurl clauses and change $release variable to the release value (4 in my case). And then it worked :)