If you're using Ogre3D, then why don't you do add another pass to the material technique that is assigned to the model, as in (suppose "ball" is an Ogre::Entity):
Ogre::MaterialPtr ptr = ball->getSubEntity(0)->getMaterial();
Ogre::Pass * pass = ptr->getTechnique(0)->createPass();
This will add a red wireframe that gets drawn over the existing material. And if you just want a wireframe, not a wireframe on top of the current material, just substitute "getPass(0)" for "createPass()"
Or, if you would rather do it in the .material file:
// first pass