3D invigorator is the only option to bring in 3d objects.
However, if your model has tons of polygons, 3d invigorator and AE will not be
able to handle the operation of any sort and it will run out of memory.
For a while I tried that exact senario myself only to find that there is so much
limitation with this method, especially if your 3d model is very complex.
Look into the 3d invigorator because it can do some great things, of course, all
depending on what you want to do exactly.
Good luck