Instead of using a 800x600 resolution LCD panel, we replace it by a new one with 1024x768. It is because a 800x600 LCD couldn't show all contents of Mac OSX Yosemite.
After we install the new LCD, we rearrange the wires as shown in the above picture. Then we attached the LCD with the main body of the iBook.
Now, the LCD was connected to the body of iBook. And it was booting Mac OSX Yosemite.
We have a video about this iBook G3 booting Mac OSX Yosemite: