Getting it is one point, here I can help you:
http://http.us.debian.org/debian/pool/main/g/glibc/
http://http.us.debian.org/debian/poo...5-11.8_all.deb
http://ftp.gnu.org/pub/gnu/glibc/
Making it work is another problem
(like dependencies for this previous deb)
You can recompile it from source (I think you need an old binutils/gcc) and to be sure not to break things you can begin by
./configure --prefix=/tmp
then manually modify /etc/ld.so.conf to add /tmp/lib
Using the deb there is an option to install the package somewhere else, you can also do it like this.
AFAIK they're should be no problem to have 2 glibc in the same directory but its critical files so be sure what you do.