Magic Mouse: replace single finger swiping/scrolling with two finger swiping/scrolling
MagicPrefs (http://magicprefs.com) version 2.4.2 did the trick for me. Choose "Preferences" in the menu it puts in the upper right of the menu bar, then click on the "Configure Scrolling" button, and then uncheck the row of checkboxes to the right of the label "One Finger Scrolling:"

No more scrolling with one finger!

Sadly, as the app notes, you can no longer use "momentum scrolls", where the page keeps scrolling after you have lifted up your fingers. You can't have it all, I guess.