Because the 32-bit packages is not part of the 64-bit directory structure so you need to make a CentOS32.repo file. Use your existing /etc/yum.repos.d/CentOS-Base.repo file as your guide and make the changes. This is an example for the first entry;
Code:
[c5-base32]
name=CentOS-5
mirrorlist=http://mirrorlist.centos.org/?release=5&arch=$i386&repo=os
gpgcheck=0
enabled=0
gpgkey=http://mirror.centos.org/centos/RPM-GPG-KEY-centos5
Repeat for the rest and save then when done try again: yum install glibc glibc.i386 --enablerepo=c532*
.