Some time later, I realized that the keyboard of X61 was not working. I think that it was working when I installed iDeneb.
It is because official OSX doesn't support PS/2 interface anymore. So, OSX doesn't load PS/2 driver. To fix, PS/2 fix needs to be applied.
For more information about PS/2 fix: http://iphonetool.blogspot.com/2009/02/hackintosh-x61-updated-to-1056.html
In some document, it will make the PS/2 interface work to edit /etc/rc. But, it was not working for me, since I can't find /etc/rc in my X61.
For more information about editing /etc/rc: