Just in case anyone else needs an answer to this, I figured out a way to do it (although I still don't know if there's a better way of doing it):

I used a JDBC writer with a mySQL driver, and at the end of the connection string I added the following:

&generateSimpleParameterMetadata=true&rewriteBatchedStatements=true

Without rewriteBatchedStatements it would go incredibly slowly, and without generateSimpleParameterMetadata it would warn me about a lack of metadata.