Does anyone know if it’s possible to add an external dictionary or text file to aka.listen rather than having to input a word or phrase one by one in a message box?

Any help would be great…thanks.

This external is for both words and phonemes.
The easiest and most efficient way is to specify your words and/or their order in a grammar text file. Look at any *.gram file example and do the same thing with your own words. These files are in the distribution.
Basically each word has to be separated by a parenthesis; each possibility (or) by a I.
For advanced users, more info about the grammar syntax here :

http://java.sun.com/products/java-media/speech/forDevelopers/JSGF/JSGF.html

You first have to record the voice into a buffer~ using record~ for instance. You can then do the speech recognition. Try using two instances and silence detection for switching from one to another if you want an audio stream to be recognized.