MS Ergonomic Keyboard has very nice slider between hands. Unfortunately this slider by default is set to be zoom option. It would be infinitely more useful to assign scroll to this, so you don’t have to move your hand to mouse every time you need to scroll your web-page.
To change the slider function follow the instructions:

1. Go to c:\Program Files\Microsoft IntelliType Pro\ (This is the usual place where the keyboard software is installed, could be different on your computer)
2. Find commands.xml
3. This file is a mapping file for keyboard, it says what each key will do in different applications.
4. There are many occurances of C319 Type=”6″ and C320 Type=”6″. Usually they look like this: <C319 Type=”6″ Activator=”ZoomIn” />.
5. Replace all ZoomIn and ZoomOut for ScrollUp and ScrollDown

Or just download the file commands.xml