Is there a way to change the Automap size option in Diablo 2 via command line or key binding?

I want to be able to push a button or type a quick command to switch from the minimap to the fullscreen map. The Toggle Minimap keybind option does not do this, it just switches what side of the screen the automap shows up on when its size is set to minimap.

Is this possible?

Unfortunately no. You have the ability to toggle the map on and off (Automap), the fade levels, party/minions and names, etc. There's also the control to toggle minimap which is what you're describing and it goes from left to right as you've mentioned. Unfortunately, there is no way to switch from the large map to the small map without using the configure menu.

Sucky, I know, but hopefully this wont be the case in Diablo 3.