How do you enable MouseKeys without using the mouse?
You can use the same menus and buttons you would if you were turning on MouseKeys using the mouse, but using them from the keyboard instead. There are a lot of standard keyboard shortcuts that you can use to navigate around without the mouse:


Ctrl + F2 to go to the Apple menu
Arrow keys and Return to choose an item from the pull down menus
Ctrl + F7 to cycle through the sections of a window
Tab to cycle through the controls in a section, and Space to use the highlighted button or checkbox.


This guide from the BBC's site puts it all together.