Hi Marc,
As far as reverse engineer I have tried this in Sql 2012 and it works well - I believe its called db import it memory serves and I believe that is what you are asking for hopefully. However it will only convert tables and well formed table relationships over and will not even look at views, functions or stored procedures however there might be a few exceptions. As far as MySQL it may work the same way if you have the right .net data provider setup and you use the Orm icon in the solution explorer that says DB Import. Once the database has been imported into your system via a specific Schema prefix that you choose it should also add them to the current window it you select yes. Otherwise it will go only into the object model.
I think there are basically two stages:
1. 1st is Successful importing data model (tables and primary keys and foreign key relationships and maybe a single schema name)
2. Secondly the converting back to MySQL or Sql Server from the Object model uses XSL style sheet under the covers so to speak.
For the 1st step to be successful start with a smaller data set... I usually prune unnecessary tables from the database, or I place them in a separate schema when perform an orm import. Not sure if you can place them in a separate schema in MySQL but you can copy to a new DB and then remove unneeded tables.
For the 2nd step to be successful you have to right click an empty area in the design surface and select relational view or ER model. It will then activate the necessary parts of the orm modeler to allow you to save the file and select various other languages to convert to include MySQL and sql server, or sql standard. Where the .orm extension is in the solution explorer it should allow you to right click that and check SQL Server or other options to convert to... So there are basically two steps to this conversion process. Other ideas for differentiating tables if you require schemas are to use table prefixes and then run a script to convert the tables to necessary schema by keying off the prefix. The import only imports one schema period.
Regards,
Marc Noon