What do I need before I start?
You need a pair of Red - Cyan 3d glasses!

I've got my red/cyan stereoscopic glasses sitting on my nose right in front of my eyes! Now what do I do?
Left click the stereoscopic glasses in the top right of the world view. It looks cool and retro, like this:  (Right click to turn it off). Alternately you can type Stereo(262) in the command line to turn it on and Stereo(0) to turn it off.

Now under the Camera tab of the Camera, set your camera type to one of the types containing the word "Stereo" such as for instance 'Standard Stereo'.

You now have access to the controls for the stereoscopic view. Separation, which is the distance between the eyes. And Convergence which is what one might call the 'focal point' of the stereoscopic view, the point of convergence where the two eyes are no longer separated.