Enable scrolling using hot key and left mouse button

Question

I have a Logitech M705 (marathon performance plus) mouse, plus the MK 710 Keyboard, I use Logi Options on macOS Big Sur and Mojave (2 separate macs). Recently I started to have pains on my hand /wrist and correlate them to be using frequently the Middle mouse button to scroll through many tools such as IDEs and Chrome.

I want to be able to push a hot key – such as Alt (= ⌥ option) – and to enable scrolling by (left button) clicking and dragging the mouse to any direction of the screen. Is this achievable?

Ideally I would like to avoid writing scripts or install 3rd-party tools, but I'm open if there is no other choice

Answer 1

This solution is based on a 3rd-party software Karabiner-Elements and uses Ctrl+Mouse motion to scroll wheel. (credits to timeSmith)

1. Download Karabiner-Elements*
2. Install it and open it (see docs about Security & Privacy System Preferences)
3. On Devices, make sure (only) the Logitech devices are selected: USB Receiver (Logitech) - mouse and keyboard type
4. Import these mouse_motion_to_scroll rules (browser > Karabine)
5. Enable only Change control + mouse motion to scroll wheel (rev 1) Complex modification rule
6. Tune the speed to 200% or as desired
7. (optional) On Functional > select Use all F1, F2, etc as standard function keys to avoid changing the behavior of these keys.

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* tested on macOS Mojave (10.14.x), using v12.10.0; for Catalina (10.15.x), use v13.7.0