What sort of 3D are we talking about here Anaglyphic?
I would love to believe there was some kind of magic batch software process for that but I can't see how it would work.
Ady's 3D Jabba Easter egg was very labour intensive and hands on but with all respect to him it's still rather flat in places even with all that work.
As he said you'd really need the best source materials to work from to get the best effect (I'm not quite getting what you are hoping to get from VHS).
While we are talking 3D on Saturday last, I went to a marvelous party, with Kiki and Johnny and Paul (sorry got a bit Noel Coward there).
It was a monochrome theme party with black and white food and black and white clothes and black and white balloons.
There was a video projector (which was projecting a Mae West film) and someone had the idea of holding up a couple of balloons and the effects were incredible (concave and convex depending on if you looked into the balloon or at the surface.
Now if someone were to make translucent forms and project onto them and film the result from two angles and composite the filmed elements you could create an interesting 3D image from a 2D source but it would still be hard work and wouldn't look like the original film in 3D but it would make for an interesting work of cinema based Anaglyphic art.