Default templates can be found, for example, in D3DX9 headers - XEXTENSIONS_TEMPLATES (and others). But I warn you to think twice before tieing yourself to .X file format. Newest SDK from MS switched to more streamlined (and not so generic) ".SDKMesh" format.

And .X always was more "intermediate" format than production one. It's easy to use it while in development because of it's flexibility, but loading and pasring all this stuff in production code...