command-line tool to convert DTD to XSD?

For historical reasons, we maintain some XML schemas in the form of DTD files, rather than XSD. I have used the "Create Schema" command inside Visual Studio to convert the file to an XSD file, which I'm then running xsd.exe on to create .NET classes. I would like to automate this process as part of our build. Is there a command-line tool which will do the same conversion