It sounds like you lost the original UV mapping when you converted the model in Blender; probably your best bet would be to convert it using Lightwave - assuming, of course, that it was actually UV mapped originally. I've had problems retaining correct UV mapping of LW models in Blender, as well.

If the textures end up distorted after using UV Mapper, the answer is probably to remap using a different scheme (planar as opposed to cylindrical, etc.); you can also shift polys and points around in the UV map itself in order to reduce distortion.

I'd suggest posting this in the UV Mapper forum; someone with more experience than I could probably help you out.