swirling particle effect

Anyone have an idea how to make a swirling particle effect? Something like a wormhole of sorts that I can later instantiate ships coming out of. I imagine it has to do with billboard textures and rotation, but don't know how to make the particles do what I want.

http://www.unifycommunity.com/wiki/index.php?title=Particle_Spiral_Effect

The updated link is :

" http://wiki.unity3d.com/index.php?title=Particle_Spiral_Effect "