How do you enable MouseKeys without using the mouse? Recently, I had to shut down a Mac with no mouse and only a PC keyboard with no Eject key.  (Incidentally, there are several solutions to that puzzle, and the one I settled on was to use the Terminal.) But as I first approached the problem, I thought: There is some universal access feature there to help if one can't use the mouse, isn't there? Yes: MouseKeys.  However, this nice page with the keyboard shortcuts for MouseKeys in Lion suggests that you have to enable a checkbox in a System Preferences pane before you can use it. So, how do you enable MouseKeys without using a 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.