I don't know who gave you that advice, and why, so I can't speak to that.
The first thing I note is that -when searching for "hibernate sql dialect"- I find something mentioned called "org.hibernate.dialect.MySQLDialect". So the first approach might be to replace what you have with that, and see where that leads you.
As to C3PO, it's a database connection pool library like Apache DBCP and others. If what you're coding is a web app -and thus has multiple users- you will want to use such a pool. More info about it can be found at
http://www.mchange.com/projects/c3p0/