There is a difference between mixing in 5.1, binaural, and spatial positioning in reference to environmental audio psychoacoustics vis-a-vis a stereo output.
First, I will talk about what I believe Freakwncy is speaking about... spatial positioning psychoacoustics through a stereo output. Then, I will discuss briefly binaural recording, and then 5.1
1. I believe Freakwncy is referring to the possibility of spatial modelling in a 360 degree plane, meaning forward, backward, etc., positioning, using not simply Doppler algorithms, but a more advanced version like this plug-in that claims it uses Hrtf to enable a person to draw in a sound position, and its time of travel along a predicated route on X, Y, Z planes:
http://www.thedirectxfiles.com/manufacturers/spinaudio_3dPanner Motion Effects.htm
That is a VST/DX plugin claiming to have the ability to what I stated through a stereo output. This method is usually most effective when utilising headphones, however, the algorithm quality of the software is dependent on the company making the product.
With a spatial positioning plugin, you can draw a travelling sound going behind your head, above you, etc.
I think the above is what Freakwncy wants, a plugin that will enable him to route audio and place it in a stereo field.
2. Binaural recording is a process of placing microphones by a dummy head of a person, where the ears would be, and having two microphones resembling two ears picking up an oscillating wave. Thus, the presence of the fake head essentially gives the listener a more "realistic" sound when the L and R signals are mixed in. This is a much more complicated process, and there are different methods of placing the microphones, and not using the dummy head, etc., but I will not get into it here. Many engineers who have mastered binaural recording cling to the secrets they know and will only do work for you if you hire them and are not present in the studio when they record. A Google search may help you find the basics.
3. 5.1 recording and mixing and mastering is a complicated process that is very involved and requires a lot of techical expertise. It is tough to properly mix and master this, and I assume that this is not necessarily what Freakwncy needs. Also a "plug-in" will not simply make a mix 5.1. It is MUCH more complicated than that. Trust me.
Sincerely,
God