Is there a way to enable SLI in Minecraft?

I'm using the GLSL shaders and I would really like to get at least 60 FPS. I'm currently at 40 on Ultra and 25-30 with HDR (or Godrays) enabled. But I have a whole 'nother card in there that's just sitting there doing nothing. It seems kinda ridiculous that I'm not using it to its full potential.

I found an NVidia Inspector config online, but that actually seems to decrease the FPS. What can I do?