iRedMail with existing MySQL installation

==== Required information ====
- iRedMail version: 0.8.6
- Store mail accounts in which backend (LDAP/MySQL/PGSQL): MySQL
- Linux/BSD distribution name and version: CentIOS 6.5
- Related log if you're reporting an issue:
====

Trying to install iRedMail with an existing installation of mySQL community ver 5.5. It still tries to install mysql 5.1.

I saw in installation tips page (very old though) that one can change that behavior but those parameters are not available in the config files created in ~/iRedMail-0.8.6/config/.

Any help is appreciated.