How to decrease trackpad tracking speed on demand?

I'm using separate magic trackpad and (still, but that's not a requirement) Mac OS 10.9.5. I'm looking for some convenient and free way to decrease tracking speed on demand, for example via additional gesture or a keystroke.

I'm a developer, so, quite often I need to precisely move cursor one-two pixels aside while inspecting layouts, picking colors, moving panels here there and currently with magic trackpad that's terrible.

One of good options I'm looking looks like this: scrolling while holding a key produces slow and precise mouse pointer movement.

Tried to search, but not very successfully:

• MagicPrefs: nothing like that, but, seems some plugin may achieve that.


• SmoothMouse: nope.


• SteerMouse: paid, does not support Apple Magic Trackpad.


• ControllerMate: paid, looks like this is what I need, but I didn't manage to achieve what I want (too much time spent).


• iMouseFix: nope.

As an option I could make some script up and bind it to the keys, which will change tracking speed or an entire app, but I'm not sure about that and consider that as a last resort. Don't like additional mouse option for precise movements, also I rarely use macbook's built-in trackpad, so I need something universal.