The keyboard itself is dependent on chords based on the physical keys on the Twiddler. Chords can be expressed by using 0LMR notation - 0 for 0 keys pressed in that row, L for left, M for middle, and R for right. Each row of 3 keys on the front can join a chord. So, for example, the default chord for "z" can be shown as M00L.
You can use an 0LMR chord to output any arbitrary text or keyboard function you'd like. However, the functionality you've described can be accomplished by using a "hotstring" program. There are numerous examples with AutoIt for Windows, and there's a plethora of other examples for any OS. Just search the interwebs for "hotstrings" and you'll find many solutions.
Given the design of the Twiddler, it'd probably be best to use your keys and chords for typing, and then stack hotstring and other functional enhancers on top, as needed - otherwise, you may lose valuable chords on specific words or phrases.
That being said, there are certain words and phrases that occur often enough to warrant at least considering including unique chords. Check out -http://twiddler.tekgear.com/doc/doku.php?id=tuner_advanced
And finally, check out -http://rhodesmill.org/brandon/projects/tabspace-guide.pdf
This looks like a great map. BTW, I'm new too - the documentation site is stellar, and will likely answer a lot of your questions!