Offscreen Rendering

Hey ColourOfDarkness,
it seems I’m at the point you’ve been two years ago.
You write

What do you mean with appropriately configured?
I’m aware that 3d geometry is rendered spatial when using any camera. But how can I control the eye separation and convergence? At the GDC2011 Nvidia document they provide a stereoscopic projection matrix:

.
                |            p11           0   0  0 |
Stereo Matrix = |             0           p22 p32 0 |
                |      p13+separation      0  p33 1 |
                | -separation*convergence  0  p34 0 |

Is it sufficient to change the standard camera projection matrix according to this to activate and control stereoscopic rendering?
And what about playback of prerendered 3d content, like 3d side by side images or movies? How can one handle this?