Sorry if this reply is a bit late for you but I was looking to do the same thing and I just found out that the MySQL Membership and Role providers are built into the new MySQL.Web.Security classes of the 5.1.x versions of MySQLConnector/Net so you shouldn't need to build a custom provider now. It creates the database tables itself the first time ...

Has anyone written any .Net 2.0 Membership Providers using EntitySpaces 2007? I was about to start re-working the default provders to take advantage of ES, when it dawned on me that someone might have already done it... Anyone?