Samsung SCH-A930
T9 - adding words.
When typing a message in T9 if you come across a word that isn't in the dictionary, switch to ABC mode, type the word you want to add, then switch back to T9 mode. The phone will automatically add the new word.
For right now, there is no way to delete words once they have been added.
Anyways, I 've found that in order to add a word to the phone's dictionary, you must switch entry modes to Abc, enter the new word, switch back immediately, and then actually send the word. It has worked this way for me so far.