Yes it is, the GT120 is "Bootcamp" compatible and therefor must work on systems using a bios. I currently use a GT120 to power my 27" Cinema Display. The video card is picked up correctly at Bios post, displays as normal and OSX detects it as the proper video card.
One thing I'm not sure of, I currently use a different boot loader called USL. This boot loader has automatic NVIDIA detection built in and doesn't require third party software to work. I actually found your post by chance as I'm unsure if this will also work with Chimera and want to give it a try.
I'm considering removing my current Raid 0 stripe set and adding 1 JBOD hard drive to confirm Multibeast+Lion compatibility...
I've attached screenshots confirming it working from my D975XBX2+USL+Snow.