Arduino communicate with PC?
I think want you to look at this function SetWindowsHookEx on Windows.  It lets you grab any mouse of keyboard input and don something,  The input still follows the normal route, you just get notified about it.

I used this function to hook the 4th and 5th buttons on my mouse to start and stop media player, so when people pestered me at work I could pause my tunes.

MSDN - SetWindowsHookEx function

StackOverflow - Example that might work