1-each strokes: repeat 15* down Or 2 make cancel gesture delay more longer, a timing ex;'countmsec' in lua + execute X times the button each time this 'countmsec'progress of 200 ms
Do you really need this function without 'stop' method included ?
You may have better luck assigning something like this to the mouse scroll wheel. Then it can be quickly repeated and controlled by the user.
Unless your idea is to actually use mouse movement to translate into keys, say for controlling a video game (i.e. mouse moves down, {DOWN} is held down until mouse stops or changes direction). If that is what you are looking for then I suggest looking for joystick/mouse emulation apps/utils.