I do not have a traditional Chinese 9210C phone at hand, and I have never tried this input method. For your information, the source code for the input method can be found in 9210 SDK at the following location:
\Symbian\6.0\NokiaCPP\DebugSource\ckon\ckfepsrc
For your convenience, I also attached its code here for your easy reference. Hopefully, it is helpful to you!