I am marshalling (serializing) JAXB beans to output stream. How can I add DOCTYPE declaration and xml processing instructions to ouput?

I am doing currently marshalling like this:

JAXBContext jaxbContext = JAXBContext.newInstance("com.example.package");
Marshaller marshaller = jaxbContext.createMarshaller();
marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, Boolean.TRUE);

SchemaFactory schemaFactory = SchemaFactory.newInstance("http://www.w3.org/2001/XMLSchema");
Schema schema = schemaFactory.newSchema(schemaSource);
marshaller.setSchema(schema);

marshaller.marshal(object, output);

I'd like have output that looks something like this:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE Something SYSTEM "some.dtd">
<?xml-stylesheet type="text/xsl" href="some.xsl"?>

JAXB bean are generated code so I don't want to change them.

There are some undocumented tricks to add the xml processing instructions and doctype. But what is the preferred or right way to do this?