I'm walking home one afternoon and it springs on me.
Here's the theory.
You use Null objects to motion track video footage.
You aim a null at two things close, and two things far, add the null objects, and bi-sect the LW camera motions to match.
I haven't actually tried it, but I hope that someone finds this usefull.
I'll be grabbin some footage soon, to test this theory and I'll pop a tutorial up.
Suggestions and Comments (as always) are welcome