Indeed, Spark is written to work with SQL Server. I am not a super expert in MySql but it seems to me that a port to MySql shouldn't be too difficult. The reason for this is that there is very little SQL Server specific code in Spark. The core data access class is named Db and this is where you will need to make some adjustments, particularly the area where new records are inserted and the newly generated Id is retrieved from the database.
To minimize the time required for the port, study the source code of Spark and familiarize yourself with MySql data access. You will also need to add some additional references to MySql specific data assemblies, but that may be all that is needed.
If you decide to pursue this path, please let us know how it goes.
I would be curious to hear if this assessment is correct.
Jack Poorte, Nov 19, 2013