Yes, Poseray is the way to go, especially if you use the default LW file structure and want to keep some separation between your LW and TG content. You can point Poseray to your Lightwave image folder(s) and export your model along with the texture images to a Terragen folder for rendering. Poseray can import LWO and export as an OBJ, which seems to be the best, at least for me (you'll probably want to convert your OBJ models to TGO (Terragen Object) format when you are satisfied with the model.
I think you will find the Lightwave/Poseray/Terragen workflow to be pretty efficient.