So I have configured it and gave it a try with Nexuiz and Openarena.
It's buggy with Nexuiz, it seems to me that it is able to create the 2 viewports, but it isn't able to resize them correctly; therefore the 2 viewports are "on top of each other" and "flickering"/"conflicting".
It works with Openarena (haven't tried it on my 3D TV yet), but the viewports are upside-down .
The performance isn't great, but I guess it is due to Xnest and 32bit chroot.
Here's a video of Openarena in case anyone is interested:
I wanted to upload it to videobin.org, but it had some kind of error so I had to resort to normal file sharing services, besides, I do not seem to be able to add attachements
My ~/.vrizerrc config so far:
setup_resolution 1024, 768
setup_viewport 0 0, 0, 512, 768
setup_viewport 1 512, 0, 512, 768
setup_eye 0 left
setup_eye 1 right