Frame Buffer — usually when people are referring to "injecting a FB" they are asking if you've forced a personality onto the driver. e.g. "Duckweed" "Gibba" -- these are two examples of valid personalities for that driver in OS X. Specifying a personality that doesn't match your card completely means it isn't configured properly, but in some cases it doesn't matter, there are instances I encountered where my card could be forced to work with Gibba or Duckweed, but only one of the DVI ports, and I'd get some stuttering when moving windows around. It turns out this is because the wrong control connection was being used, or was overlapping with another port.
I can't help configure the card with Chameleon or Chimera, it's been too long since I used either. If I were in your position right now today I would buy a card that is supported by OS X in the same layout as you can buy retail and use that. You can probably find GTX 760 cards for very low cost that will not require to use of any additional software or effort unless you wanted to use nVidia's "web drivers" instead of the ones Apple ships, but you'd also never have to be doing a song a dance with defining personalities, injecting anything, or setting special flags to the kernel between updates to the OS. For me it was money well spent to not be in a position where I had no choice but to fiddle with a hex editor or injections.
