Try out the new online Chinese IME! (tested on Firefox and Chrome)
http://chinese-ime.appspot.com/


Three Corner IME
http://zh.wikipedia.org/zh-tw/三角編號法 (in Chinese)


Enter Key
The enter key automatically fills in the rest of the code with "0".
Example: "987 Enter" is the same as typing out "987000".
Exception: "Enter" just inserts a return character, since "000000" is not a valid Three Corner code.

Wildcard
If you only remember two of the three parts of code, use the wildcard key "??" on the upper left of the keyboard. A list of candidates with their corresponding code will be shown. The list is ordered with the most frequently appearing character on top.
Example: "??9898", "98??98", "9898??"


If you have any questions or comments, please feel free to contact me.


For anyone who wants to help contribute, the URL is at https://github.com/noodlewiz/threecornerime .