We need an STEREO modifier !
Why ?
because i often have many cameras in the same scene and that all don’t have same stereoscopic settings 
+ we need the modifier to create 2 cam (left and right) so they can be used by this soft (http://www.maxunderground.com/archives/10751\_kostasoft\_sterescopic\_viewer.html) ! it aloows realtime viewport stereo monitoring !
That really productive
Unfortunately there will be issues if a modifier tries to create two cameras.
For the moment, you can use the V-Ray stereo rig controller, which allows you to have different stereo settings for your cameras, and it creates two separate cameras for each center one.
Best regards,
Vlado
Yep but no convergence at all !
Would need some more parameters
Yes, some more control would be useful, but you can already do this pretty easily (f.e. by assigning look-at targets of the left and right cameras to be the same as for the center camera).
Best regards,
Vlado