[K12OSN] Downgrading software (Mysql 5 to Mysql 4)

[Krsnendu dasa]

I have written once to this forum and twice to Koha forum without much success.
I am running K12LTSP-6 and I want to install Koha, the library
management system. Unfortunately Koha is not compatible with Mysql 5,
the version of Mysql in the yum repositories for Fedora Core 6. It is
easy enough to uninstall Mysql 5 using yum remove mysql-server but how
do I install version 4?
Do I enable the Fedora Core 4 repository and try to install using yum
or do I download the rpm and try to manually install, or do I build
from source.
When I tried the rpm method it complained of incompatible dependencies
like openssl for example.

Tips greatly appreciated. I am stuck.

Thanks.
Krsnendu dasa