I just wanted to share my noob mistake with anybody who might be searching the forums. If you are trying to use ETM in your own application and you cannot see any material on your terrain, make sure that Plugin_CgProgramManager is included in your plugins.cfg file. Otherwise, the terrain will just be blank. Also, you will see something like this in Ogre.log:
WARNING: material ETTerrainMaterial has no supportable Techniques and will be blank. Explanation:
Pass 0: Vertex program ET/Programs/VSLodMorph2 cannot be used - not supported.
Pass 0: Vertex program ET/Programs/VSLodMorph cannot be used - not supported.