Here's a small AutoHotKey script that: Note: the compiled executable must be run from Program Files on Windows Vista and newer versions of Windows, otherwise it won't work properly.

For Windows 10 (Alt+Tab and double-click - scrolling window under mouse pointer can be enabled in Settings):
WheelAltTabNoScroll32v2.exe - 32-bit version
WheelAltTabNoScroll64v2.exe - 64-bit version
WheelAltTabNoScrollv2.ahk - source code


For Windows 8.1 and older (Alt+Tab, double-click, scroll window under mouse pointer):
WheelAltTab32.exe - 32-bit version
WheelAltTab64.exe - 64-bit version
WheelAltTab.ahk - source code


For Windows 8.1 and older (scroll window under mouse pointer only):
ScrollOnly32.exe - 32-bit version
ScrollOnly64.exe - 64-bit version
ScrollOnly.ahk - source code


Update 2015-07-31:

Since Windows 10 includes the ability to scroll under mouse pointer, I made a version of the script that just implements Alt+Tab and doubleclick.

Update 2015-08-07:

Now also sends Win+Tab when Back+Forward buttons are clicked.

And by request, version that only scrolls the window under mouse pointer.

Update 2016-06-09:

All files now also include a SHA-256 signature.