“Unfortunately, the Ergonomic keyboard config utility doesn’t allow you to change the settings for the centre zoom button. In order to do so, you will have to edit the
C:\Program Files\Microsoft Intellitype Pro\commands.xml file manually. (For computers running the more recent Microsoft Mouse and Keyboard Center the path is
C:\Program Files\Microsoft Device Center\commands.xml) or C:\Program Files\Microsoft Mouse and Keyboard Center” – Tog from superuser.com
The Zoom keys in the commands.xml file are C320 for Zoom out and C319 for Zoom in.
You can use notepad++ and the Replace Dialog(Ctrl+F and select Replace tab). Check “Regular Expression” in the bottom left side of the dialog and use these to remap the zoom key:
Find what: <C319 .* />
Replace with: <C319 Type=”6″ Activator=”ScrollUp” />
Find what: <C320 .* />
Replace with: <C320 Type=”6″ Activator=”ScrollDown” />
Side note: the process is now called itype.exe. Close the process and restart it(Task Manager->File->Run new task-> “itype.exe”) for the changes to take effect.