When using maps online, I find that the Magic Mouse scrolling is oversensitive. It's hard to point or click with the Magic Mouse without scrolling so far I lose where I was on a map.
Scrolling with the Magic Mouse in documents or text pages on the web works fine.
You can switch Magic Mouse scrolling off and back on in System Settings > Accessibility > Pointer Control > Mouse Options > Use mouse for scrolling, but that's so deep in System Settings that I doubt a string of mouse clicks would work.
This is similar to Toggle Pointer (Mouse) Scrolling by changing System Prefs from a couple of years ago.
I too want to do something similar and haven't been able to. In theory you could use a command line command, but it doesn't appear to take effect without a restart.
Given that it's in Accessibility, I'm surprised that there's no keyboard shortcut built into the OS for mouse scrolling.
There is, but doesn't seem to take effect in current window or perhaps until you restart
Here's a list of Terminal commands that get into System Preferences:
But you could get as far as Accessibility with Keyboard Maestro and the View Menu. You can tab down to each sub category, but then Return doesn't equal a mouse click. Again, this seems like a long chain of KM items.