I've never heard of that extension, but try this link. It tells how to convert the extension to something more usable.

http://home.austin.rr.com/reubenrachel/reuben/3D/index.html

And apparently this one converts to .3ds and .obj which Poser can read

http://synapse-web.org/tools/xroads/xroads.stm

"It is good to see ourselves as others see us. Try as we may, we are never
able to know ourselves fully as we are, especially the evil side of us.
This we can do only if we are not angry with our critics but will take in good
heart whatever they might have to say." - Ghandi