I am creating an RDS instance using CloudFormation using this:
\"Resources\": { \"myDB\": { \"Type\": \"AWS::RDS::DBInstance\",
CloudFormation still doesn't hold any solutions for us, but hopefully they will add Database Migration Service support soon.
In the meantime, there is great solution if you're using CodePipeline: create a migration stage that invokes a Lambda function to run your migration. I stumbled across this guide for invoking Lambda from CodePipeline that may be helpful for those unfamiliar.