Depending on what type of wires you want, you can try any of the following:
1) Grid Shader: If you're using NURBS or Patches, you can apply the grid shader (texture or material shader - cannot remember which it is). The line color is the wire color, while the fill color can be set transparent. Define the number of lines in U and V to match the UV counts of your surfaces.
2) Toon shaders: Good for contour control and other criteria such as illumination boundaries, object boundaries, intersection boundaries, etc... Works as a combination lens and material shader solution.
3) OpenGL render: choose OpenGL from the render options and click "Options" in the bottom left. You can control line thickness and anti-aliasing quality. Also honors shaded vs textured vs wireframe vs etc..
4) Contour output: If you have access to mental ray v1.9, you can activate contour output to control line appearance per tesselation parameters as well as contour parameters.
5) Line renderer: Using the native softimage renderer, you can render lines to a .lin file which is a vector based format. From here, you can convert the .lin file to a pic at any resolution and line thickness (because vector formats are resolution independent). This method will take some tinkering to perfect. If your objects are polygon, you can use the tools in the Edge_Flag menus (Model and Matter modules) to prevent specified edges from rendering (or force them to render).
Hope this helps,
Matt
Matt Lind
Animator / Technical Director
Softimage certified instructor:
Softimage|3D
Softimage|XSI
speye_21@hotmail.com