Based on the information I found in this forum and tpuser (http://www.tpuser.idv.tw/wp/?p=1815
). I changed both my keyboard and palmrest of my X230 to the ones of X220. The hardware installation is generally smooth. One small trick is that the keyboard should be put in place first, than the palmrest. The reason is that there are two small bumps at the two ends of the bar where the speaker/power buttons lying, which prevent the keyboard to be installed properly if the palmrest is already installed. The hardware works well after the replacement, and the finger print reader even directly recognised my fingers without re-learning.
Even though the classical keyboard is a tad higher, there is still good clearance between the LCD screen and the keyboard. So no problem on that.
The keys on the seventh row are mostly not working, including PrtSc, ScrLk, Pause, Insert, and Home. Actually the only problem is the Home key, as other keys are non-essential. Another problem is that the keys are mis-mapped. This problem is rather easy to solve, using e.g. the software AutoHotkey. I implemented a script below. The mapping makes the PgUp, PgDn, and Delete keys to function properly. The End key was not changed, so no mapping is needed. The only missing key is the Home key, I mapped it using Ctrl-PgUp, and Ctrl-PgDn as well for the End key. I also mapped Ctrl-Delete for the Insert key, I don't know when I used it last time, but anyway.
I use a docking station, so the mapping, if not turned off, will also affect the external keyboard. The solution is to use the CapsLock key to turn the mapping on/off, rather convenient. This is also the reason that I do not use registry tweaking tool such as SharpKeys, which should be fine if you never use an external keyboard.
I don't care about the Fn+Key settings. If someone is interested in, you may hack the registry of TPHOTKEY.
So the keyboard is generally working. Of course, if someone will hack the BIOS, that will be very welcome. Nevertheless, I am pretty happy with the current state already. The most important part is the responsiveness of the keyboard, and the track pointer and the buttons are also higher, a much better ergonomic design.
Script below, if you use the classical keyboard and want to use AutoHotkey.