Just tried that above me. From the same source it seems

But it didn't work on my ATI card

I guess, you did set variable: r_StereoSupportAMD as well
r_StereoSupportAMD REQUIRE_APP_RESTART
type: int
current: 0
help: Disables/Enables [0/1] stereo support on AMD hardware
Even tho in the patchnotes for 1.9 they say:
Re-added possibility to enable r_StereoSupportAMD via config file (unsupported), it doesn't mean that Anaglyph is supported as well by now, tho.