I just got a laptop and I've installed MTW:VI on it and it works great. But...I can't figure out how to zoom the camera in (strategic or tactical maps) because, obviously, the laptop doesn't have a mouse wheel.

I went to the Assign Keys list in the Options Menu but I didn't see any keys there that seemed to have anything to do with zoom level.

Can someone please tell me how to zoom the camera in when I don't have a mouse wheel?