Before start, I will assume you have Debian sid and MySQL5 installed correctly, which will not detail within this document. In case of Debian, MySQL5 installation is just as simple as a single command:
apt-get install mysql-server-5.0 mysql-client-5.0 mysql-common
This HOWTO is highly similar as my other article which target for install Apache2.2 + PHP5.2 + OCI8/PDO_OCI from sketch on Debian sid. Therefore some duplicated section will directly refer to there, and only mention those different in case for MySQL in here.