Bought WheelClick on the App Store?
The direct version does everything the App Store one does, plus Magic Mouse gestures. Your purchase covers it. Move over for free.
It finds your App Store copy, asks for your email, installs the direct version in its place and activates it. Your settings stay. The Upgrader is open source.
Or do it without installing anything
Only the purchase receipt inside the app is sent. Nothing else leaves your Mac.