Drawing Wireframes

I have a landscape that I normally draw as fans with textures. Now I’d like to draw the landscape as a wireframe. But I don’t see right off how to draw just the outlines of fans or triangles using the fan and triangle primitives. I could use the line primitive, but that would require different and larger vertex buffers. Is there any way to draw it as a wireframe using the fan primitive and the index/vertex buffer I already have? I noticed that the SDK has a D3D sample, progressive mesh, that switches a tiger model from textured to wireframe. But I haven’t yet figured out where in that program the difference is. And I have yet found anything in the SDK docs to help me. Thanks