Although the question is too old to respond to, but may someone coming behind can get help
As mentioned in the documentation for the Database Replication Module:
Support for SQL Server 2005/2008, Oracle, PostgreSQL and Informix databases
I believe we don't have anything in the AppStore yet to connect with MySQL (new entries are always welcome!)
MySql can easily be supported however the only libraries that I know of are payed or distributed under the gpl licence.
So if you can find a mysql jdbc jar file including the mysql driver it's a relatively small change to the module to start supporting this library.
If somebody knows about a free mysql jar/driver just let some at mendix know and we'll might be able to start supporting mysql as well.