enable XmlSerializer

I am trying to make a Soap webservice in ServiceStack with a predefined xsd. This xsd can not be used with the standard DataContractSerializer because of some incompatible attributes definitions (using svcutil.exe). The XmlSerializer (using xsd.exe) works fine.
I have anabled the XmlSerializer in ServiceStack by using the XmlSerializerFormat Attribute on both the Request and Response DTO and made a check in de SoapHandler to enable the XmlSerializer.
Not sure if this is the cleanest way to implement this. But it works great.