Better still, why not code your words as TOKENS??

Store all the words you are likely to use in a table in the EEPROM in the PIC, then reference them using numbers;

Example;

PRESS, ANY, BUTTON, DOWN, THE

PRESS THE DOWN BUTTON becomes 1,5,4,3 you can delineate the words with a number say 27 as you will only ever use characters 1-26 anyhow, when the exctract routine sees a "27" it knows that is the end of the word.

Hope this helps.