MirroR is a Motion plugin for LightWave that lets you MirroR an item's channels, and optionally bake the resulting keys.
An item can also MirroR itself, so it is great for setting up fake reflections.
MirroR exposes a known limitation with LW, where scaling geometry in a negative direction will invert the normals of that geometry. An easy work around for this is to make the geometry surfaces double sided.