Is it possible to replace just keyboard, not whole top case?

Four keys on the keyboard of my unibody MacBook Pro (model A1286) do not work: 6, y, / and =. Everything else seems to be fine, and as far as I know, no liquid has ever been spilled on it. After trying a firmware update, resetting the PRAM, and other suggestions I found online, I took it to the Genius Bar at the Apple Store. Unfortunately, I'm a month beyond the warranty period.

The "Genius" there opened it up and said that there may be liquid damage, but that he was not sure, and that it looked like at the very least the entire top case assembly including keyboard would need to be replaced. (That was the best case scenario: a $310 repair to Cupertino, two week turnaround.) But he warned that if the technicians in Cupertino diagnosed it as liquid-damaged, it would cost $1249 to repair.

Reading some forums online that pointed me here, I've gotten the idea that it might be possible to keep the current top case assembly but just either clean or replace the keyboard itself. The comments on your video for the 15" 2.53ghz unibody suggested that this repair might be far too complicated. Any thoughts on this?

BTW, even though your video was for A1286 model, the computer I have (which clearly says A1286 on the back) does not have a separate panel for the batter or the hard drive; the entire back is one solid piece. The video is very useful in giving me a sense of the complexity of the task, but I'm worried it might be even more difficult if I have a model A1286 that's even different from the one in your video.

Are there any steps you'd suggest I take, or any diagnostics I can do myself?