You can't make the generator pick up the type this way. It (or rather the Slick code that reverse engineers the Model from the database schema) currently only detects a hand full of types and simply assumes String for all other ones. This will be improved in the future. In order to make it use a different type for a column you have to customize the generator. The corresponding Slick documentation example actually shows how to customize the type:
http://slick.typesafe.com/doc/2.0.0/code-generation.html#customization