BrainModular

Did anyone ever think to a binaural panner which utilizes head related impulse responses in Usine?

no ! but I did a project with surround panners that feed a 5.1 to binaural VST :

http://north-america.beyerdynamic.com/virtual-studio/

more here : http://sonsdanslair.free.fr/multiphonie/plugins.htm

Interesting Oli, very interesting.
I have to point out that I probably didn't explain very well. I mean a binaural spatializer such as the glorious longcat H3D. It would be awesome and really inspiring inside Usine.
Nay!!tell something!

I tested, very quikly, the Oculus Spatialiser. it seems to be very useful and sound pretty good. More here.

But it doesn't work with Usine. It didn't appear in the plugin

Last year i bought Binauralizer, from noise maker. It works great, but there is no way to adjust z distance.

I did the same thing! Binauraliser doesn't have z distance.
For the oculus plugin problem I wrote to oculus staff and they told me because it works only in 64 bit daw.
There are more and more vst working great and available for free as 3D audio for virtual reality has become the scepter of war that has just begun among google - facebook (who recently acquired threebigears) and other digital brands.
Technologies are evolving and with them the methods of threating hrir impulses. It's not an easy job but interpolating hrir is not so hard if you know the thing. If usine staff could make a library object that uses one of the awesome public HRIR libraries would be remarkably. The most evolved platforms don't have it (4 example Max only have user projects that do such a thing). The world is now listen trhough headphones, audio software developers should surf this wave that won't end so soon as 3d audio is the future of audio. When 2.0 listening format will cease to be the standard it's only a matter of time.

PS: @Cmodica: I don't know if oculus canhandle multiple sources in one instance. Does it?