Program Wide Key replacement Is there a way to quickly replace the middle mouse button click with something like mouse button 5? 

I looked around and found this middle mouse key alternative.
It would be nice if I could change the emulated: 3 Button Mouse from Alt + LMB to mouse button 5.

Is it possible to change a button or shortcut program wide?
I can recommend an application like X-Mouse Button Control, it allows you to assign any virtual key / shortcut to any mouse button (per program or globally), I use it to trigger some special Blender features (like Render Only) by mouse side buttons.