That one's a little different, it's not exactly a command because you can do it while another command is still running.

This will do it:

[Shortcut Keys]
Space=script:moi.view.resetAll();

That's basically a little script macro that will run when you push the space bar.

You've probably already seen this, but just to make sure - when you do the view reset the first time, it will go to the selected objects. If you want to go to all objects instead of just the selected ones, then do another reset immediately and it will switch to all objects.

- Michael