Actually, that's pretty easy; the file is generated by the operating system, and contains just one word: either "open" or "closed". You'll need to gain root access, then edit the file with your favorite editor and change the word to "closed", at which point (hopefully) it will then believe that the keyboard is closed. However, I just tried this on my N900, and the OS immediately set it back to "open", so I don't know just how well this technique will work for you.