@João Hornburg:
No, fn+Shift+F11 doesn't work. Tested in Ubuntu 12.04, it doesn't even work as a regular Print Screen key. The key mappings in the Apple page you reference are apparently not all implemented by the Linux “apple” key layout. Also, if fn+Shift+F11 were Print Screen/SysRq, would it be possible to add the Alt modifier?
@João Hornburg:
No, fn+Shift+F11 doesn't work. Tested in Ubuntu 12.04, it doesn't even work as a regular Print Screen key. The key mappings in the Apple page you reference are apparently not all implemented by the Linux “apple” key layout. Also, if fn+Shift+F11 were Print Screen/SysRq, would it be possible to add the Alt modifier?