This Lightwave 3D corner pinning plugin takes up to 4 nulls and exports their 2D screen positions into keyframes for import into Avid DS or Autodesk IFFFS (Inferno, Flame, Flare, Flint, Smoke) tracker nodes.
Pick your objects, set the export location, and click Export. Select all 4 objects to get corner-pinning data for Tracker nodes in DS or 4-Corner Surfaces in Action on Smoke/Flame, or use one or two if you just need need X/Y screen coordinates to drive some other effect.
PinnedDown can also convert 24/30 fps keys into 23.98/29.97 for those that like to work in whole-number Frames Per Second inside Lightwave (LW10 has some new and exciting bugs dealing with fractional framerates) but are actually comping for broadcast.
This plugin should work on Lightwave 3D versions 6 and up, though I've only tested it as far back as Lightwave 9.6. Windows only, for 32 and 64-bit.