So why do you want to install yum on a rhel box if you already have up2date? Well there are a number of reasons, the main one and the reason I wrote this is that I was installing openvz and it needed yum installed. Trying to just use the yum rpm or source compiling was getting all sorts of python errors. I decided to just grab the centos 4 rpms. Note this is not going to be used for updating, up2date still is used for that.
Just copy/paste the commands
mkdir /usr/local/src/yum
cd /usr/local/src/yum
wget http://centos.cs.ucr.edu/centos/4/apt/i386/RPMS.os/python-urlgrabber-2.9.6-2.noarch.rpm
wget http://centos.cs.ucr.edu/centos/4/apt/i386/RPMS.os/python-sqlite-1.1.6-1.i386.rpm
wget http://centos.cs.ucr.edu/centos/4/apt/i386/RPMS.os/python-elementtree-1.2.6-4.i386.rpm
wget http://centos.cs.ucr.edu/centos/4/apt/i386/RPMS.os/python-urlgrabber-2.9.6-2.noarch.rpm
wget http://centos.cs.ucr.edu/centos/4/apt/i386/RPMS.os/centos-yumconf-4-4.3.noarch.rpm
wget http://centos.cs.ucr.edu/centos/4/apt/i386/RPMS.os/yum-2.4.0-1.centos4.noarch.rpm
wget http://centos.cs.ucr.edu/centos/4/apt/i386/RPMS.os/sqlite-3.2.2-1.i386.rpm
rpm -Uvh *rpm
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<출처: http://www.eth0.us/yum-rhel >