Stereographic Projection How ?

[NNois]

Hi,
I'm on a thing where i output a lat/long map out of the 3d, then idealy in the comp software i would pixel/blend this to a "Stereographic Projection" (little planet effect http://2008.sub.blue/blog/2010/6/17/little_planets.html).

My plan was putting a camera in a sphere mapped with the environment map, to permit cool camera movement in comp
I'm stucked in nuke where i can Spherical transform the projection but i can't find the right Stereographic projection mode.

What i'm missing here ? Is there a pixel blender plugin somewhere where i can put a formula or something like that ?
Do someone know or had had already some experience in this before ??

[NNois]

For what it worth i've solved the little world part, the setup is rather simple
in nuke:
1. an environment map
2. a shootcam of the env map
3. re-mapped on a sphere
4. A CAMERA litteraly on top of the sphere looking at the inside, this, give you a live "little world"

[Bullit]

Something that i never did.
But thanks for feedback NNois .