I just double clicked the script you made available for download, it installed and that was it. I didnt tweak the settings any more so I should be active. When I press T nothing happens. Keyboard viewer shows I typed T.
What I actually would be able to accomplish in photoshop is the following:
Hold down a random key, which could be T for instance, and have Photoshop activate CONTROL+OPTION+LEFT MOUSE BUTTON DRAG. That actions corresponds to changing the brush size on the fly. Then I could simply hover my stylus on my tablet and brush size could be modified.
If the LEFT MOUSE BUTTON DRAG is out of question, then simply holding any key to activate CONTROL+OPTION would be fine, I would just have to actually press the stylus down the tablet to send the drag command (which I would rather hover but that’s not a big deal)