Hello,
first I want to say that I really like Twiddler and for the most part it has solved most of my back problems. that being said, as a digital artist I find myself constantly use the ALT + Space combination when using photoshop. at the moment I have to assign space to be one of the "finger buttons" but I would very much like to be able to reassign the NUM modifier key as Space - so I could use both ALT and Space with just my thumb.